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': 'Central Chemoreceptors are most sensitive to following changes in blood: \nSelect and explain. \nA. T PCO2, B. I PCO2, C. TH+, D. T PO2', 'role': 'user'}, {'content': 'Answer: A \nExplanation: T PCO2', 'role': 'assistant'}]