The correct answer is A, AWS CodeCommit. AWS CodeCommit is a fully managed source control service by AWS that hosts private Git repositories. It is designed to make it easier for development teams to work together and manage their source code in a secure and scalable way. The service eliminates the need to manage your own version control system infrastructure, providing a managed service that allows you to store and collaborate on code securely. The other options, AWS CodeBuild, AWS CodeDeploy, and AWS CodeStar, are related to the development process but do not provide a fully hosted version control service.