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': 'Naltrexone is: March 2013 \nSelect and explain. \nA. (mu) agonist, B. 6 (delta) agonist, C. lc (kappa) antagonist, D. NOP receptor antagonist', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C i.e. lc antagonist Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence and opioid dependence.', 'role': 'assistant'}]