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
Early and reliable indication of air embolism during anaesthesia can be obtained by continuous monitoring of: 
Select and explain. 
A. ECG, B. Blood pressure, C. End Tidal CO2, D. Oxygen saturation
C: End Tidal CO2
Answer: C: End Tidal CO2 
Explanation: End Tidal CO2