This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 2, Subject name: Physiology
[{'content': 'The PO2 (in mm Hg) inside skeletal muscle cells during exercise is closest to: \nSelect and explain. \nA. 3, B. 10, C. 20, D. 30', 'role': 'user'}, {'content': "Answer: A \nExplanation: The PO2 (in mm Hg) inside skeletal muscle cells during exercise is closest to - 3mm Hg The PO2 decreases severly due to muscle's oxygen demand is very high.", 'role': 'assistant'}]