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 can be used for prophylaxis of migraine except : \nSelect and explain. \nA. Sumatriptan, B. Valproate, C. Propranolol, D. Topiramate', 'role': 'user'}, {'content': "Answer: A \nExplanation: 'Sumatriptan is the drug of choice for acute severe migraine but it is not indicated for prophylaxis'.", 'role': 'assistant'}]