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
Varenicline acts by ? 
Select and explain. 
A. Paial nicotine receptor agonist, B. Nicotine receptor antagonist, C. Both agonist and antagonist at nicotine receptor, D. None of the above
A: Paial nicotine receptor agonist
Answer: A: Paial nicotine receptor agonist 
Explanation: Ans. is 'a' i.e., Paial nicotine receptor agonist Varenicline It is paial agonist at the nicotine receptor. It is used in nicotine addicts.