diff --git a/src/answer/answer.controller.ts b/src/answer/answer.controller.ts
new file mode 100644
index 0000000..5b0795d
--- /dev/null
+++ b/src/answer/answer.controller.ts
@@ -0,0 +1,47 @@
+import { Controller, Get, Post, Patch, Delete, Param, Body, UsePipes, ValidationPipe, Query, ParseUUIDPipe, HttpCode, HttpStatus,} from '@nestjs/common';
+import { AnswerService } from './answer.service';
+import { CreateAnswerDto } from './dto/create-answer.dto';
+import { UpdateAnswerDto } from './dto/update-answer.dto';
+import { Answer } from './entity/answer.entity';
+
+@Controller('answers')
+export class AnswerController {
+  constructor(private readonly answerService: AnswerService) {}
+
+  @Post()
+  @UsePipes(new ValidationPipe({ transform: true, whitelist: true }))
+  async create(@Body() body: CreateAnswerDto): Promise<Answer> {
+    return this.answerService.create(body);
+  }
+
+  @Get('findAll')
+  async findAll(
+    @Query('page') page: string = '1',
+    @Query('limit') limit: string = '10',
+  ) {
+    // The service returns the full pagination object
+    return this.answerService.findAll(parseInt(page, 10), parseInt(limit, 10));
+  }
+
+  @Get(':id')
+  async findOne(
+    @Param('id', new ParseUUIDPipe()) id: string,
+  ): Promise<Answer | null> {
+    return this.answerService.findById(id);
+  }
+
+  @Patch(':id')
+  @UsePipes(new ValidationPipe({ transform: true, whitelist: true }))
+  async update(
+    @Param('id', new ParseUUIDPipe()) id: string,
+    @Body() body: UpdateAnswerDto,
+  ): Promise<Answer | null> {
+    return this.answerService.update(id, body);
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  async remove(@Param('id', new ParseUUIDPipe()) id: string): Promise<void> {
+    return this.answerService.remove(id);
+  }
+}
diff --git a/src/answer/answer.module.ts b/src/answer/answer.module.ts
new file mode 100644
index 0000000..830cc17
--- /dev/null
+++ b/src/answer/answer.module.ts
@@ -0,0 +1,16 @@
+import { Module } from '@nestjs/common';
+import { MongooseModule } from '@nestjs/mongoose';
+import { AnswerService } from './answer.service';
+import { AnswerController } from './answer.controller';
+import { Answer, AnswerSchema } from './entity/answer.entity';
+
+@Module({
+  imports: [
+    MongooseModule.forFeature([
+      { name: Answer.name, schema: AnswerSchema },
+    ]),
+  ],
+  controllers: [AnswerController],
+  providers: [AnswerService],
+})
+export class AnswerModule {}
diff --git a/src/answer/answer.service.ts b/src/answer/answer.service.ts
new file mode 100644
index 0000000..045606a
--- /dev/null
+++ b/src/answer/answer.service.ts
@@ -0,0 +1,81 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { InjectModel } from '@nestjs/mongoose';
+import { Model } from 'mongoose';
+import { Answer, AnswerDocument } from './entity/answer.entity';
+import { CreateAnswerDto } from './dto/create-answer.dto';
+import { UpdateAnswerDto } from './dto/update-answer.dto';
+import { PaginateModel } from '../participant/participant.service';
+
+@Injectable()
+export class AnswerService {
+  constructor(
+    @InjectModel(Answer.name)
+    private readonly answerModel: PaginateModel<AnswerDocument>,
+  ) {}
+
+  async create(data: CreateAnswerDto): Promise<Answer> {
+    const answer = new this.answerModel({
+      ...data,
+      id: data.id || undefined, // Let BaseEntity generate UUID if not provided
+      metadata: data.metadata || { entries: [] },
+    });
+    return answer.save();
+  }
+
+  async findAll(
+    page = 1,
+    limit = 10,
+  ): Promise<{
+    docs: Answer[];
+    totalDocs: number;
+    limit: number;
+    page: number;
+    totalPages: number;
+    hasNextPage: boolean;
+    hasPrevPage: boolean;
+    nextPage: number | null;
+    prevPage: number | null;
+  }> {
+    return this.answerModel.paginate(
+      {},
+      { page, limit, lean: true },
+    );
+  }
+
+  async findById(id: string): Promise<Answer | null> {
+    const answer = await this.answerModel
+      .findOne({ id })
+      .lean()
+      .exec();
+    if (!answer) {
+      throw new NotFoundException(`Answer with ID "${id}" not found`);
+    }
+    return answer;
+  }
+
+  async update(
+    id: string,
+    data: UpdateAnswerDto,
+  ): Promise<Answer | null> {
+    const updatedAnswer = await this.answerModel
+      .findOneAndUpdate(
+        { id },
+        { $set: { ...data, updatedAt: new Date() } },
+        { new: true },
+      )
+      .lean()
+      .exec();
+
+    if (!updatedAnswer) {
+      throw new NotFoundException(`Answer with ID "${id}" not found`);
+    }
+    return updatedAnswer;
+  }
+
+  async remove(id: string): Promise<void> {
+    const result = await this.answerModel.deleteOne({ id }).exec();
+    if (result.deletedCount === 0) {
+      throw new NotFoundException(`Answer with ID "${id}" not found`);
+    }
+  }
+}
diff --git a/src/answer/dto/create-answer.dto.ts b/src/answer/dto/create-answer.dto.ts
new file mode 100644
index 0000000..d2513b2
--- /dev/null
+++ b/src/answer/dto/create-answer.dto.ts
@@ -0,0 +1,13 @@
+import { IsString, IsUUID} from 'class-validator';
+import { BaseDto } from '../../_core/dto/base.dto';
+
+export class CreateAnswerDto extends BaseDto{
+  @IsUUID()
+  participantId: string;
+
+  @IsUUID()
+  questionId: string;
+
+  @IsString()
+  value: string;
+}
diff --git a/src/answer/dto/update-answer.dto.ts b/src/answer/dto/update-answer.dto.ts
new file mode 100644
index 0000000..f073f58
--- /dev/null
+++ b/src/answer/dto/update-answer.dto.ts
@@ -0,0 +1,4 @@
+import { PartialType } from '@nestjs/mapped-types';
+import { CreateAnswerDto } from './create-answer.dto';
+
+export class UpdateAnswerDto extends PartialType(CreateAnswerDto) {}
diff --git a/src/answer/entity/answer.entity.ts b/src/answer/entity/answer.entity.ts
new file mode 100644
index 0000000..b735b40
--- /dev/null
+++ b/src/answer/entity/answer.entity.ts
@@ -0,0 +1,44 @@
+import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
+import { Document } from 'mongoose';
+import { BaseEntity } from 'src/_core/entity/_base.entity';
+import * as mongoosePaginate from 'mongoose-paginate-v2';
+import { v4 as uuidv4 } from 'uuid';
+
+@Schema({ _id: false, id: false }) // Disable _id and virtual id
+export class Answer extends BaseEntity {
+  @Prop({
+    type: String,
+    default: () => uuidv4(),
+    required: true,
+    immutable: true,
+  })
+  participantId: string;
+
+  @Prop({
+    type: String,
+    default: () => uuidv4(),
+    required: true,
+    immutable: true,
+  })
+  questionId: string; // form can be identified based on question
+
+  @Prop({
+    type: String,
+    required: true,
+  })
+  value: string;   //value can be mapped to option based on question type
+
+
+}
+
+export type AnswerDocument = Answer & Document;
+export const AnswerSchema = SchemaFactory.createForClass(Answer);
+AnswerSchema.plugin(mongoosePaginate);
+
+// Transform the output to remove the internal '_id'
+AnswerSchema.set('toJSON', {
+  transform: (doc: AnswerDocument, ret: Answer & { _id?: any }) => {
+    delete ret._id;
+    return ret;
+  },
+});
diff --git a/src/attachment/attachment.service.ts b/src/attachment/attachment.service.ts
index e8d9aab..30188a0 100644
--- a/src/attachment/attachment.service.ts
+++ b/src/attachment/attachment.service.ts
@@ -4,24 +4,8 @@ import { Model } from 'mongoose';
 import { Attachment, AttachmentDocument } from './entity/attachment.entity';
 import { CreateAttachmentDto } from './dto/create_attachment.dto';
 import { UpdateAttachmentDto } from './dto/update_attachment.dto';
+import { PaginateModel } from '../participant/participant.service';
 
-// Interface matching the mongoose-paginate-v2 plugin
-interface PaginateModel<T> extends Model<T> {
-  paginate: (
-    query?: any,
-    options?: { page: number; limit: number; lean?: boolean; select?: string },
-  ) => Promise<{
-    docs: T[];
-    totalDocs: number;
-    limit: number;
-    page: number;
-    totalPages: number;
-    hasNextPage: boolean;
-    hasPrevPage: boolean;
-    nextPage: number | null;
-    prevPage: number | null;
-  }>;
-}
 
 @Injectable()
 export class AttachmentService {
@@ -54,20 +38,15 @@ export class AttachmentService {
     prevPage: number | null;
   }> {
     // Selects all fields from the Attachment entity for the response
-    const selectFields =
-      'id text type isRequired isConfidential validationRules options attachments metadata status createdAt updatedAt';
     return this.attachmentModel.paginate(
       {},
-      { page, limit, lean: true, select: selectFields },
+      { page, limit, lean: true },
     );
   }
 
   async findById(id: string): Promise<Attachment | null> {
-    const selectFields =
-      'id text type isRequired isConfidential validationRules options attachments metadata status createdAt updatedAt';
     const attachment = await this.attachmentModel
       .findOne({ id })
-      .select(selectFields)
       .lean()
       .exec();
     if (!attachment) {
@@ -80,15 +59,12 @@ export class AttachmentService {
     id: string,
     data: UpdateAttachmentDto,
   ): Promise<Attachment | null> {
-    const selectFields =
-      'id text type isRequired isConfidential validationRules options attachments metadata status createdAt updatedAt';
     const updatedAttachment = await this.attachmentModel
       .findOneAndUpdate(
         { id },
         { $set: { ...data, updatedAt: new Date() } },
         { new: true },
       )
-      .select(selectFields)
       .lean()
       .exec();
 
diff --git a/src/option/option.service.ts b/src/option/option.service.ts
index cdd6007..27c567b 100644
--- a/src/option/option.service.ts
+++ b/src/option/option.service.ts
@@ -1,28 +1,10 @@
 import { Injectable } from '@nestjs/common';
 import { InjectModel } from '@nestjs/mongoose';
-import { Model } from 'mongoose';
 import { CreateOptionDto } from './dto/create-option.dto';
 import { UpdateOptionDto } from './dto/update-option.dto';
 import { Option, OptionDocument } from './entity/option.entity';
-import { PaginateQuery, Paginated, paginate } from 'nestjs-paginate';
+import { PaginateModel } from '../participant/participant.service';
 
-
-interface PaginateModel<T> extends Model<T> {
-  paginate: (
-    query?: any,
-    options?: { page: number; limit: number; lean?: boolean; select?: string },
-  ) => Promise<{
-    docs: T[];
-    totalDocs: number;
-    limit: number;
-    page: number;
-    totalPages: number;
-    hasNextPage: boolean;
-    hasPrevPage: boolean;
-    nextPage: number | null;
-    prevPage: number | null;
-  }>;
-}
 @Injectable()
 export class OptionService {
   constructor(
@@ -48,7 +30,7 @@ export class OptionService {
   }> {
     return this.optionModel.paginate(
       {},
-      { page, limit, lean: true, select: 'id metadata status text createdAt updatedAt' },
+      { page, limit, lean: true },
     );
   }
 
diff --git a/src/participant/participant.service.ts b/src/participant/participant.service.ts
index b4e0cef..85ce749 100644
--- a/src/participant/participant.service.ts
+++ b/src/participant/participant.service.ts
@@ -6,7 +6,7 @@ import { Participant, ParticipantDocument } from './entity/participant.entity';
 import { UpdateParticipantDto } from './dto/update-participant.dto';
 import { v4 as uuidv4 } from 'uuid';
 
-interface PaginateModel<T> extends Model<T> {
+export interface PaginateModel<T> extends Model<T> {
   paginate: (
     query?: any,
     options?: { page: number; limit: number; lean?: boolean; select?: string },
@@ -52,12 +52,12 @@ export class ParticipantService {
   }> {
     return this.participantModel.paginate(
       {},
-      { page, limit, lean: true, select: 'id metadata status userId role displayName createdAt updatedAt' },
+      { page, limit, lean: true},
     );
   }
 
   async findById(id: string): Promise<Participant | null> {
-    return this.participantModel.findOne({ id }).select('id metadata status userId role displayName createdAt updatedAt').lean().exec();
+    return this.participantModel.findOne({ id }).lean().exec();
   }
 
   async update(id: string, data: UpdateParticipantDto): Promise<Participant | null> {
@@ -66,10 +66,7 @@ export class ParticipantService {
         { id },
         { $set: { ...data, updatedAt: new Date() } },
         { new: true },
-      )
-      .select('id metadata status userId role displayName createdAt updatedAt')
-      .lean()
-      .exec();
+      ).lean().exec();
   }
 
   async remove(id: string): Promise<void> {
diff --git a/src/participantGroup/dto/create-participantGroup.dto.ts b/src/participantGroup/dto/create-participantGroup.dto.ts
new file mode 100644
index 0000000..312f6d0
--- /dev/null
+++ b/src/participantGroup/dto/create-participantGroup.dto.ts
@@ -0,0 +1,12 @@
+import { IsString, IsEnum, IsOptional, IsUUID, ValidateNested } from 'class-validator';
+import { Type } from 'class-transformer';
+import { MetadataDto } from '../../_core/dto/metadataEntry.dto';
+import { BaseDto } from '../../_core/dto/base.dto';
+
+export class CreateParticipantGroupDto extends BaseDto{
+  @IsString()
+  title: string; // Required, provided by client
+
+  @IsEnum(['confidential','delphi','one-time-question','one-time-section','one-time-page','one-time-form'])
+  type: 'confidential'|'delphi'|'one-time-question'|'one-time-section'|'one-time-page'|'one-time-form';
+}
\ No newline at end of file
diff --git a/src/participantGroup/dto/update-participantGroup.dto.ts b/src/participantGroup/dto/update-participantGroup.dto.ts
new file mode 100644
index 0000000..610d1b1
--- /dev/null
+++ b/src/participantGroup/dto/update-participantGroup.dto.ts
@@ -0,0 +1,4 @@
+import { PartialType } from '@nestjs/mapped-types';
+import { CreateParticipantGroupDto } from './create-participantGroup.dto';
+
+export class UpdateParticipantGroupDto extends PartialType(CreateParticipantGroupDto) {}
diff --git a/src/participantGroup/entity/participantGroup.entity.ts b/src/participantGroup/entity/participantGroup.entity.ts
new file mode 100644
index 0000000..7ca69a0
--- /dev/null
+++ b/src/participantGroup/entity/participantGroup.entity.ts
@@ -0,0 +1,31 @@
+import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
+import { BaseEntity } from 'src/_core/entity/_base.entity';
+import * as mongoosePaginate from 'mongoose-paginate-v2';
+import { Document } from 'mongoose';
+
+@Schema({ _id: false, id: false }) // Disable _id and virtual id
+export class ParticipantGroup extends BaseEntity {
+  @Prop({
+    type: String,
+    required: true,
+  })
+  title: string;
+
+  @Prop({
+    type: String,
+    enum: ['confidential','delphi','one-time-question','one-time-section','one-time-page','one-time-form'],
+    // default: '',
+    required: true,
+  })
+  type: 'confidential'|'delphi'|'one-time-question'|'one-time-section'|'one-time-page'|'one-time-form';
+}
+
+export type ParticipantGroupDocument = ParticipantGroup & Document;
+export const ParticipantGroupSchema = SchemaFactory.createForClass(ParticipantGroup);
+ParticipantGroupSchema.plugin(mongoosePaginate);
+ParticipantGroupSchema.set('toJSON', {
+  transform: (doc: ParticipantGroupDocument, ret: ParticipantGroup & { _id?: any }) => {
+    delete ret._id;
+    return ret;
+  },
+});
\ No newline at end of file
diff --git a/src/participantGroup/participantGroup.controller.ts b/src/participantGroup/participantGroup.controller.ts
new file mode 100644
index 0000000..f74a9b1
--- /dev/null
+++ b/src/participantGroup/participantGroup.controller.ts
@@ -0,0 +1,53 @@
+import { Controller, Get, Post, Patch, Delete, Param, Body, UsePipes, ValidationPipe, Query, ParseUUIDPipe } from '@nestjs/common';
+import { ParticipantGroupService } from './participantGroup.service';
+import { CreateParticipantGroupDto } from './dto/create-participantGroup.dto';
+import { UpdateParticipantGroupDto } from './dto/update-participantGroup.dto';
+import { ParticipantGroup } from './entity/participantGroup.entity';
+
+@Controller('participantGroupGroups')
+export class ParticipantGroupController {
+  constructor(private readonly participantGroupService: ParticipantGroupService) {}
+
+  @Post()
+  @UsePipes(new ValidationPipe({ transform: true }))
+  async create(@Body() body: CreateParticipantGroupDto): Promise<ParticipantGroup> {
+    return this.participantGroupService.create(body);
+  }
+
+  @Get('findAll')                                                           // returns non uuid id !!!
+  async findAll(
+    @Query('page') page: string = '1',
+    @Query('limit') limit: string = '10',
+  ): Promise<{
+    docs: ParticipantGroup[];
+    totalDocs: number;
+    limit: number;
+    page: number;
+    totalPages: number;
+    hasNextPage: boolean;
+    hasPrevPage: boolean;
+    nextPage: number | null;
+    prevPage: number | null;
+  }> {
+    return this.participantGroupService.findAll(parseInt(page), parseInt(limit));
+  }
+
+  @Get(':id')
+  async findOne(@Param('id', new ParseUUIDPipe()) id: string): Promise<ParticipantGroup | null> {
+    return this.participantGroupService.findById(id);
+  }
+
+  @Patch(':id')
+  @UsePipes(new ValidationPipe({ transform: true }))
+  async update(
+    @Param('id', new ParseUUIDPipe()) id: string,
+    @Body() body: UpdateParticipantGroupDto,
+  ): Promise<ParticipantGroup | null> {
+    return this.participantGroupService.update(id, body);
+  }
+
+  @Delete(':id')
+  async remove(@Param('id', new ParseUUIDPipe()) id: string): Promise<void> {
+    return this.participantGroupService.remove(id);
+  }
+}
\ No newline at end of file
diff --git a/src/participantGroup/participantGroup.module.ts b/src/participantGroup/participantGroup.module.ts
new file mode 100644
index 0000000..88adc23
--- /dev/null
+++ b/src/participantGroup/participantGroup.module.ts
@@ -0,0 +1,14 @@
+import { Module } from '@nestjs/common';
+import { MongooseModule } from '@nestjs/mongoose';
+import { ParticipantGroupService } from './participantGroup.service';
+import { ParticipantGroupController } from './participantGroup.controller';
+import { ParticipantGroup, ParticipantGroupSchema } from './entity/participantGroup.entity';
+
+@Module({
+  imports: [
+    MongooseModule.forFeature([{ name: ParticipantGroup.name, schema: ParticipantGroupSchema }]),
+  ],
+  controllers: [ParticipantGroupController],
+  providers: [ParticipantGroupService],
+})
+export class ParticipanGrouptModule {}
\ No newline at end of file
diff --git a/src/participantGroup/participantGroup.service.ts b/src/participantGroup/participantGroup.service.ts
new file mode 100644
index 0000000..7877e7e
--- /dev/null
+++ b/src/participantGroup/participantGroup.service.ts
@@ -0,0 +1,60 @@
+import { Injectable } from '@nestjs/common';
+import { InjectModel } from '@nestjs/mongoose';
+import { Model } from 'mongoose';
+import { CreateParticipantGroupDto } from './dto/create-participantGroup.dto';
+import { ParticipantGroup, ParticipantGroupDocument } from './entity/participantGroup.entity';
+import { UpdateParticipantGroupDto } from './dto/update-participantGroup.dto';
+import { v4 as uuidv4 } from 'uuid';
+import { PaginateModel } from '../participant/participant.service';
+
+
+@Injectable()
+export class ParticipantGroupService {
+  constructor(
+    @InjectModel(ParticipantGroup.name)
+    private readonly participantGroupModel: PaginateModel<ParticipantGroupDocument>,
+  ) {}
+
+  async create(data: CreateParticipantGroupDto): Promise<ParticipantGroup> {
+    const participantGroup = new this.participantGroupModel({
+      ...data,
+      id: data.id || undefined, // Let BaseEntity generate UUID
+      metadata: data.metadata || { entries: [] },
+    });
+    return participantGroup.save();
+  }
+
+  async findAll(page = 1, limit = 10): Promise<{                              // returns non uuid id !!!
+    docs: ParticipantGroup[];
+    totalDocs: number;
+    limit: number;
+    page: number;
+    totalPages: number;
+    hasNextPage: boolean;
+    hasPrevPage: boolean;
+    nextPage: number | null;
+    prevPage: number | null;
+  }> {
+    return this.participantGroupModel.paginate(
+      {},
+      { page, limit, lean: true },
+    );
+  }
+
+  async findById(id: string): Promise<ParticipantGroup | null> {
+    return this.participantGroupModel.findOne({ id }).lean().exec();
+  }
+
+  async update(id: string, data: UpdateParticipantGroupDto): Promise<ParticipantGroup | null> {
+    return this.participantGroupModel
+      .findOneAndUpdate(
+        { id },
+        { $set: { ...data, updatedAt: new Date() } },
+        { new: true },
+      ).lean().exec();
+  }
+
+  async remove(id: string): Promise<void> {
+    await this.participantGroupModel.deleteOne({ id }).exec();
+  }
+}
\ No newline at end of file
diff --git a/src/question/question.service.ts b/src/question/question.service.ts
index a2230b8..a0eee9e 100644
--- a/src/question/question.service.ts
+++ b/src/question/question.service.ts
@@ -4,24 +4,7 @@ import { Model } from 'mongoose';
 import { Question, QuestionDocument } from './entity/question.entity';
 import { CreateQuestionDto } from './dto/create-question.dto';
 import { UpdateQuestionDto } from './dto/update-question.dto';
-
-// Interface matching the mongoose-paginate-v2 plugin
-interface PaginateModel<T> extends Model<T> {
-  paginate: (
-    query?: any,
-    options?: { page: number; limit: number; lean?: boolean; select?: string },
-  ) => Promise<{
-    docs: T[];
-    totalDocs: number;
-    limit: number;
-    page: number;
-    totalPages: number;
-    hasNextPage: boolean;
-    hasPrevPage: boolean;
-    nextPage: number | null;
-    prevPage: number | null;
-  }>;
-}
+import { PaginateModel } from '../participant/participant.service';
 
 @Injectable()
 export class QuestionService {
@@ -54,20 +37,15 @@ export class QuestionService {
     prevPage: number | null;
   }> {
     // Selects all fields from the Question entity for the response
-    const selectFields =
-      'id text type isRequired isConfidential validationRules options attachments metadata status createdAt updatedAt';
     return this.questionModel.paginate(
       {},
-      { page, limit, lean: true, select: selectFields },
+      { page, limit, lean: true },
     );
   }
 
   async findById(id: string): Promise<Question | null> {
-    const selectFields =
-      'id text type isRequired isConfidential validationRules options attachments metadata status createdAt updatedAt';
     const question = await this.questionModel
       .findOne({ id })
-      .select(selectFields)
       .lean()
       .exec();
     if (!question) {
@@ -80,15 +58,12 @@ export class QuestionService {
     id: string,
     data: UpdateQuestionDto,
   ): Promise<Question | null> {
-    const selectFields =
-      'id text type isRequired isConfidential validationRules options attachments metadata status createdAt updatedAt';
     const updatedQuestion = await this.questionModel
       .findOneAndUpdate(
         { id },
         { $set: { ...data, updatedAt: new Date() } },
         { new: true },
       )
-      .select(selectFields)
       .lean()
       .exec();