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: Surgery
Following drugs are known immunosuppressive agent except - 
Select and explain. 
A. Prednisolone, B. Cephalosporin, C. Azathioprine, D. Cyclosporin - A
B: Cephalosporin
Answer: B: Cephalosporin 
Explanation: None