This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
[{'content': 'Capnography is useful for – \nSelect and explain. \nA. Determining Vaporizer malfunction or contamination, B. Determining circuit hypoxia, C. Determining the appropriate placement of endotracheal tube, D. Detecting concentration of oxygen in the anesthetic circuit.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Uses of Capnography\n\nIt is the surest confirmatory sign of correct intubation in the trachea. Incorrect position of the tube in oesophagus instead of the trachea (oesophagal intubation) will yield ETCO2 = 0.\nIntraoperative displacement of endotracheal tube → ETCO2 will become zero.\nObstruction or disconnections of endotracheal tube → ETCO2 will fall.\nDiagnosing malignant hyperthermia → ETCO2 increases significantly (more than 100 mg Hg).', 'role': 'assistant'}]