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: Medicine
[{'content': 'A cardiac patient must be asked to stop one of the following drugs when he is coughing a lot \nSelect and explain. \nA. Diltiazem, B. Aspirin, C. Enalapril, D. Clopidogrel', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]