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': 'Which is Cytochrome P450 inhibitor? \nSelect and explain. \nA. Ketoconazole, B. Rifampicin, C. Phenytoin, D. INH', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Impoant microsomal enzyme inhibitors are: Valproate Ketoconazole Cimetidine Ciprofloxacin Erythromycin Isoniazid Ref: K.D.T 6th Ed Page 27,28.', 'role': 'assistant'}]