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': 'The function of Carotid body is \nSelect and explain. \nA. Measures the change in PO2 in arterial blood, B. Measures PO2 in venous blood, C. Measures the change in CO2 in arterial blood, D. Measures the change in CO2 in venous blood', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]