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: Medicine
[{'content': 'Drugs used in treatment of essential tremor are all, EXCEPT: \nSelect and explain. \nA. Primidone, B. Propranolol, C. Botulinum toxin, D. None of the above', 'role': 'user'}, {'content': "Answer: D \nExplanation: Many cases are mild and require no treatment other than reassurance. Occasionally, tremor can be severe and interfere with eating, writing, and activities of daily living. Primidone (25-1000 mg/d) and propranolol (20-80 mg/d) are the standard drug therapies and can be administered alone or in combination. Alprazolam, gabapentin, topiramate, clonazepam, clozapine, and nimodipine have been repoed to improve tremor in some patients. Botulinum toxin injections may be helpful for limb or voice tremor, but treatment can be associated with muscle weakness. Surgical therapies targeting the VIM nucleus of the thalamus can be very effective in severe and drug-resistant cases. Ref: Harrison's principle of internal medicine 17th edition, chapter 367.", 'role': 'assistant'}]