Which action is performed on the user story if the deployment is completed successfully?

When a deployment is completed successfully, moving the user story to the next environment is the standard action. This process is a key component of continuous integration and deployment practices. It ensures that the user story undergoes further testing and validation in various environments, typically progressing from development through staging and eventually to production.

Moving the user story to the next environment allows teams to maintain a streamlined workflow, ensuring that changes are not only implemented but also tested in a controlled manner. This action helps in identifying any issues early in the process before they impact production, thereby improving overall software quality and delivery speed.

The other options present actions that do not accurately reflect the typical process following a successful deployment. For instance, keeping it in the same environment would halt progress, while revalidating or archiving signifies different processes that are not standard for handling a successfully deployed user story.