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
Presence of trifluroacetic acid (TFA) in urine indicates that volatile anaesthetic agent used was 
Select and explain. 
A. Halothane, B. Methoxyflurane, C. Trichloroethylene, D. None of the above
A: Halothane
Answer: A: Halothane 
Explanation: Ans. is 'a' i.e., Halothane