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: Anaesthesia
[{'content': 'Best antagonist of morphine is \nSelect and explain. \nA. Nalorphine, B. Naloxone, C. Buprenorphine, D. Pentazocine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Naloxone', 'role': 'assistant'}]