This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Principles of Gas Exchange -  Respiratory Membrane, Subject name: Physiology
[{'content': 'pO2 pressure at sea level: \nSelect and explain. \nA. 140, B. 150, C. 160, D. 180', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) 160* At sea level the atmosphere exerts a total pressure of 760mmHg. Since the atmosphere is 21% 02 (by volume), the partial pressure of oxygen (pO,)= 0.21 x 760 = 160 mmHg.* The partial pressure of C02 (pC02) at sea level is 0.23 mmHg.', 'role': 'assistant'}]