Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 587 discussion

https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-use-lambda-authorizer.html

Option C: Configure an Amazon API Gateway endpoint in front of an Amazon Kinesis Data Firehose that stores the information that the company receives in an Amazon S3 bucket. Use an API Gateway Lambda authorizer to resolve authorization. This solution meets the requirements in the following ways: Handles Unpredictable Traffic: Amazon Kinesis Data Firehose can handle variable amounts of streaming data and automatically scales to accommodate sudden increases in traffic. Integration with Web Applications: Amazon API Gateway provides a RESTful API endpoint for integrating with web applications. Authorization: An API Gateway Lambda authorizer provides the necessary authorization step to secure API access. Data Storage: Amazon Kinesis Data Firehose can deliver data directly to an Amazon S3 bucket for storage, making it suitable for long-term analytics and predictions.

https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-use-lambda-authorizer.html

B. Amazon Kinesis Data Firehose does not save anything

Configure an Amazon API Gateway endpoint in front of an Amazon Kinesis Data Firehose that stores the information that the company receives in an Amazon S3 bucket. Use an API Gateway Lambda authorizer to resolve authorization.

Using ECS just to stores the information is a overkill. So B or C then, lambda authoriser is the key word => C

https://docs.aws.amazon.com/lambda/latest/dg/services-kinesisfirehose.html

C authorizer is configured for the method. If it is, API Gateway calls the Lambda function. The Lambda function authenticates the caller by means such as the following: Calling out to an OAuth provider to get an OAuth access token

lambda authoriser seems to be logical solution.