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
Capnography is useful for 
Select and explain. 
A. Determining Vaporizer malfunction or contamination, B. Determining circuit hypoxia, C. Determining the appropriate placement of endotracheal, D. Detecting concentration of oxygen in the anesthetic circuit.
C: Determining the appropriate placement of endotracheal
Answer: C: Determining the appropriate placement of endotracheal 
Explanation: capnography is the ideal method of determining the correct placemet of endotracheal tube. Identification : loss of waveform of capnogram.decline in End tidal CO2 levels.