This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transplantation, Subject name: Surgery
[{'content': 'The most commonly used drug in the immunosuppression of renal transplant patients is cyclosporine. A major side effect of this drug is: \nSelect and explain. \nA. Pancytopenia, B. Constipation, C. Nephrotoxicity, D. Amenorrhea', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ironically, nephrotoxicity is the major problem associated with the use of cyclosporine. Despite this fact, it is the most commonly used immunosuppressive drug in renal transplant patients.', 'role': 'assistant'}]