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': 'Drug of choice for rapid cyclers in manic-depressive psychosis is - \nSelect and explain. \nA. Carbamazepine, B. Valproate, C. Phenytoin, D. Lithium', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Valproate o Valproate is paicularly useful for rapid cyclers.", 'role': 'assistant'}]