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': 'At toxic doses, zero order kinetics is seen in: \nSelect and explain. \nA. Penicillin, B. Phenytoin, C. Valproate, D. Carbamazepine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]