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: Psychiatry
[{'content': 'Drug of choice for rapid cyclers is \nSelect and explain. \nA. Lithium, B. Sodium valproate, C. Carbamazepine, D. Amitryptaline', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sodium valproate is the drug of choice for rapid cyclers.\nRapid cyclers has 4 or more than 4 episodes of mania, depression or hypomania in 1 year.', 'role': 'assistant'}]