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
[{'content': 'Capnography basically monitors- \nSelect and explain. \nA. Central venous pressure, B. Blood pressure during anesthesia, C. Concentration of exhaled CO2, D. Concentration of inhaled O2', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Capnography monitores end tidal CO2 levels ( CO2 in Exhaled gas ) It is based on the principle of absorption spectrophotometry . Normal levels of EtCO2 is 35-45mmg', 'role': 'assistant'}]