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': 'Flat capnogram found in A/E \nSelect and explain. \nA. Disconnection of anesthetic tubing, B. Accidental extubation, C. Mechanjca1 ventilation failure, D. Bronchospasm', 'role': 'user'}, {'content': 'Answer: D \nExplanation: in bronchospasm,there is prolonged expiratory upstroke(abscence of phase 3 plateau). in tube displacement,disconnection,accidental extubation,ventilation failure,it is flat.', 'role': 'assistant'}]