Which must be measured regularly to identify variances from the plan?

Obviously D. Project Performance. For more clarity, A. Stakeholder requirements DO NOT change that often unless there's a major change of plan. B. Project controls are those steps that you implement to ensure performance. C. Control Schedule are those aspects that you envisage prior to execution of the project plan. 

My answer is for option C. Control Schedule

Of course it is D - Project Performance .

My answer is A, all stakeholders requirements

Thank for the invitation. More convenient choice is Option D - Project performance.

Thank you for the invitation. My answer is D

Option D - Project performance.

Thank you. I seem option D-Project performance is good answer.