This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intravenous Anesthetic Agents, Subject name: Anaesthesia
[{'content': 'All intravenous anaesthetic agents can cause histamine release except- \nSelect and explain. \nA. Thiopentone, B. Propofol, C. Etomidate, D. Ketamine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: With exception to etomidate, all IV induction agents have been alleged to cause some histamine. However, the incidence of severe anaphylaxsis is is extremely rare to currently available IV agents.', 'role': 'assistant'}]