This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concepts in physiology, Subject name: Physiology
[{'content': 'Most impoant buffer in interstitial fluid: \nSelect and explain. \nA. Phosphate, B. Bicarbonate, C. Histidine, D. Protein', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Principal buffers in body fluids: Blood H2CO3 = H+ + HCO3-HProt complex = H+ + Prot-HHb= H+ + Hb- Interstitial fluid H2CO3=H+ + HCO3- Intracellular fluid HProt complex = H+ + Prot-H2PO4- = H+ + HPO42-', 'role': 'assistant'}]