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
Flat capnogram found in A/E 
Select and explain. 
A. Disconnection of anesthetic tubing, B. Accidental extubation, C. Mechanjca1 ventilation failure, D. Bronchospasm
D: Bronchospasm
Answer: D: Bronchospasm 
Explanation: in bronchospasm,there is prolonged expiratory upstroke(abscence of phase 3 plateau). in tube displacement,disconnection,accidental extubation,ventilation failure,it is flat.