This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'Most common drug used for prophylaxis of migraine is \nSelect and explain. \nA. Sumatriptan, B. Propranolol, C. Valproate, D. Flunarizine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: HL Sharma 3rd ed Pg no: 191 beta blockers are the first line of choice for chronic migraine or migraine prophylaxis', 'role': 'assistant'}]