You are in charge of developing an application that will make use of AWS services. There is a key requirement from an architecture point of view that the entire system should be decoupled to ensure less dependency. Which of the following are the suitable services to decouple different components of an application?

Answer options:

A.AWS CodePipeline
B.AWS Simple Queue Service
C.AWS Simple Notification Service
D.AWS CodeBuild
E.AWS CodeStar

Answer – B and C
The AWS Documentation mentions the following.
Amazon Simple Queue Service (Amazon SQS) offers a secure, durable, and available hosted queue that lets you integrate and decouple distributed software systems and components. Amazon SQS offers common constructs such as dead-letter queues and cost allocation tags.
Amazon SNS enables you to modernize your applications and decouple them into smaller, independent components that are easier to develop, deploy and maintain. AWS SNS topics can be subscribed to by multiple decoupled services. SNS is mostly used in conjunction with SQS to provide decoupled services.
Option A is incorrect since this service is used to build CI/CD pipelines for integration and deployment.
Option D is incorrect since this service is used as the build and test stage of the CI/CD deployments.
Option E is incorrect since AWS CodeStar is a cloud-based service for creating, managing, and working with software development projects on AWS. 
For more information on the Simple Queue Service, please refer to the below link-
https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/welcome.html
https://aws.amazon.com/sns