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: Forensic Medicine
[{'content': 'The drug which is used for long-term maintenance in opioid addiction: AIIMS 06; Punjab 09; AI 11 \nSelect and explain. \nA. Nalorphine, B. Naloxone, C. Butarphanol, D. Methadone', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Methadone', 'role': 'assistant'}]