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
Anaphylaxis is caused by 
Select and explain. 
A. N2O, B. Althesin, C. Halothane, D. Propofol
B: Althesin
Answer: B: Althesin 
Explanation: AlthesinAlthesis is a neurosteroidIt was used as a parenteral anaestheticIt was withdrawn from the market because of several severe anaphylactic reactions(Refer: Morgan and Mikhail's Clinical Anaesthesiology, 5th edition)