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': 'Varenicline acts by ? \nSelect and explain. \nA. Paial nicotine receptor agonist, B. Nicotine receptor antagonist, C. Both agonist and antagonist at nicotine receptor, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Paial nicotine receptor agonist Varenicline It is paial agonist at the nicotine receptor. It is used in nicotine addicts.", 'role': 'assistant'}]