This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Preoperative assessment and monitoring in anaesthesia, Subject name: Anaesthesia
[{'content': 'Most common cause for end tidal CO2 falls due to \nSelect and explain. \nA. Cardiac arrest, B. Extubation, C. Hypothermia, D. Hyperhermia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The most common cause for fall in EtCO2 levels is accidental extubation.', 'role': 'assistant'}]