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 of the following is used as an antidote to nicotine poisoning \nSelect and explain. \nA. Neostigmine, B. Atropine, C. Phentolamine, D. Trimethaphan', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref: HL Sharma 3rd ed pg:195 Nicotine is an agonist for NN receptors Ganglion blockers are antagonists for NN receptors eg: hexamethonium, trimethaphan, Mecamylamine etc', 'role': 'assistant'}]