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
[{'content': 'True about azathioprine is : \nSelect and explain. \nA. It has more anti tumor effect than immunosuppressant effect, B. It is not a prodrug, C. It selectively affects differentiation of T cells, D. It is a pyrimidine antimetabolite', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]