This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following immunosuppressive agent requires monitoring of renal function on regular basis ? 
Select and explain. 
A. Azathioprine, B. Mycophenolate mofetil, C. Methotrexate, D. Cyclosporine A
D: Cyclosporine A
Answer: D: Cyclosporine A 
Explanation: None