This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anaesthesia
[{'content': 'Anaphylaxis is caused by \nSelect and explain. \nA. N2O, B. Althesin, C. Halothane, D. Propofol', 'role': 'user'}, {'content': "Answer: B \nExplanation: AlthesinAlthesis is a neurosteroidIt was used as a parenteral anaestheticIt was withdrawn from the market because of several severe anaphylactic reactions(Refer: Morgan and Mikhail's Clinical Anaesthesiology, 5th edition)", 'role': 'assistant'}]