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': 'Breast feeding is contraindicated if the mother is taking: \nSelect and explain. \nA. Iron tonics, B. Iron tonics, C. Crystalline penicillin, D. Phenytoin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Phenytoin', 'role': 'assistant'}]