Which tool should a developer use to integrate AWS service features directly into an application?

Explanations:

AWS SDK provides APIs for developers to integrate AWS services directly into applications.

AWS CodeDeploy is used for automating code deployments, not directly for integrating AWS services.

AWS Lambda is a compute service to run code in response to events, not for general AWS service integration.

AWS Batch is a service for running batch computing jobs, not for integrating AWS services into applications.