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': 'True about naltrexone is all except: \nSelect and explain. \nA. Acts on opioid receptors, B. Is used in treatment of alcohol dependence, C. Is used to reduce craving in dependence, D. Is an opioid agonist', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]