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': "Which drug is not used now in Alzheimer's disease \nSelect and explain. \nA. Tacrine, B. Galantamine, C. Donepezil, D. Rivastigmine", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Because of hepatotoxicity,and requirements of frequent dosing,tacrine is less often used than other agents Ref-KDT 6/e p104,472,473', 'role': 'assistant'}]