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': 'In a patient taking oral contraceptive, the chance of pregnancy increases after taking any of the following drugs except - \nSelect and explain. \nA. Phenytoin, B. Griseofulvin, C. Ampicillin, D. Cimetidine', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Cimetidine", 'role': 'assistant'}]