This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Anaesthesia
[{'content': 'Endotracheal tube in the esophagus is best assessed by: \nSelect and explain. \nA. Chest wall movement, B. Auscultation, C. CO2 Exhalation, D. Chest tube passes through vocal cords', 'role': 'user'}, {'content': 'Answer: C \nExplanation: For sure shot confirmation of endotracheal tube Capnography is used. ET tube in trachea (capnography) While if almost Flat line appears - Et tube is in esophagus.', 'role': 'assistant'}]