A rollback plan is a part of the project management plan that defines how to revert the system to its previous state or baseline if the change or migration fails or causes unacceptable impacts1. A rollback plan is different from a contingency plan, which is a plan to deal with a specific risk event that may or may not occur2. A release plan and a deployment plan are not relevant to the scenario, as they are used to plan and execute the delivery and installation of the system, not to undo them. Therefore, the correct answer is A . Rollback plan.