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: Physiology
[{'content': 'One intern calculated the concentration of O2 in blood as 0.0025 ml/ml of blood. Considering atmospheric pressure as 760mmHg, how much approximate O2 tension could have been in the blood? \nSelect and explain. \nA. 40 mmHg, B. 60 mmHg, C. 80 mmHg, D. 100 mmhg', 'role': 'user'}, {'content': 'Answer: C \nExplanation: For PO2 to be 100mmHg, the dissolved O2 level has to be around 0.30ml/dL of blood.\nSo when the O2 level is 0.25ml/dL, the PO2 is around 80mmHg.', 'role': 'assistant'}]