Which of the following defines how the project scope should be created, executed, monitored and controlled, and then validated?

Scope variance plan is not a recognized artifact in the PMBOK framework and does not exist as a standard project management document.

The Scope Management Plan is a subsidiary component of the Project Management Plan that provides guidance on how scope will be defined, how the WBS will be developed, how deliverables will be validated, and how scope changes will be controlled. It governs every phase of scope work from initial definition through formal acceptance, making it the single document that covers all the activities listed in the question.

The Staffing Management Plan (Resource Management Plan) addresses acquiring, developing, and releasing project team members and physical resources, not scope activities.

The Schedule Management Plan defines how the project schedule will be developed and controlled, which is a separate concern from managing project scope.