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': 'All of the following drugs undergo hepatic metabolism before excretion EXCEPT: \nSelect and explain. \nA. Phenytoin, B. Diazepam, C. Penicillin G, D. Cimetidine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]