You created an update for your application on App Engine. You want to deploy the update without impacting your users. You want to be able to roll back as quickl...

You created an update for your application on App Engine. You want to deploy the update without impacting your users. You want to be able to roll back as quickly as possible if it fails. What should you do?

A. Delete the current version of your application. Deploy the update using the same version identifier as the deleted version. B. Notify your users of an upcoming maintenance window. Deploy the update in that maintenance window. C. Deploy the update as the same version that is currently running. D. Deploy the update as a new version. Migrate traffic from the current version to the new version.