The correct answer is B.
OBJ-3.4.1: A stage plan is created towards the end of the preceding stage as part of the managing a stage boundary process. It is produced close to the time when the planned events will take place. A stage plan is created at the level of detail needed to enable the day-to-day control by the project manager. A stage plan is required for each management stage, not for the whole project. The stage plan provides the basis for the project manager’s control. The project board monitors against the project plan.