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 most important buffer in RBC is \nSelect and explain. \nA. O2Hb + Na hemoglobinate, B. O2Hb + K hemoglobinate, C. H2CO3 + KHCO3, D. H2CO3 + NaHCO3', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]