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': 'Anesthesia agent with least analgesic propey \nSelect and explain. \nA. N20, B. Halothane, C. Ether, D. Propane', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Halothane', 'role': 'assistant'}]