This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
[{'content': 'Which of the following opioids has maximum plasma protein binding capacity? \nSelect and explain. \nA. Morphine, B. Sufentanil, C. Fentanyl, D. Pethidine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sufentanil has maximum plasma protein binding among opioids. Refer kDT 6/e', 'role': 'assistant'}]