A development team set up a pipeline to launch a test environment. The developers want to automate tests for their application. The team created an AWS CodePipeline stage to deploy the application to a test environment in batches using AWS Elastic Beanstalk. A later CodePipeline stage contains a single action that uses AWS CodeBuild to run numerous automated Selenium-based tests on the deployed application. The team must speed up the pipeline without removing any of the individual tests.
Which set of actions will MOST effectively speed up application deployment and testing?

A. Set up an all-at-once deployment in Elastic Beanstalk. Run tests in parallel with multiple CodeBuild actions.
B. Set up a rolling update in Elastic Beanstalk. Run tests in serial with a single CodeBuild action.
C. Set up an immutable update in Elastic Beanstalk. Run tests in serial with a single CodeBuild action.
D. Set up a traffic-splitting deployment in Elastic Beanstalk. Run tests in parallel with multiple CodeBuild actions.