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': 'Anaesthetic agent which is explosive in the presence of cautery – \nSelect and explain. \nA. Nitrous oxide, B. Ether, C. Trilene, D. Halothane', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]