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 in Alzheimer's disease \nSelect and explain. \nA. Tacrine, B. Gallantamine, C. Donepezil, D. Rivastigmine", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Refer kDT 6/e p 102,472,473 Because of hepatotoxicity, and requirement of frequent dosing, Tekken is less often used than other agents', 'role': 'assistant'}]