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: Surgery
[{'content': 'Presence of trifluroacetic acid (TFA) in urine indicates that volatile anaesthetic agent used was \nSelect and explain. \nA. Halothane, B. Methoxyflurane, C. Trichloroethylene, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Halothane", 'role': 'assistant'}]