This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal physiology, Subject name: Physiology
[{'content': 'In proximal tubule, HCO3 is absorbed with the step of \nSelect and explain. \nA. Na+ Cl cotranspoer, B. Na+ - K+2Cl contraspoer, C. Na+ - H+ exchanger, D. Na+ -K+ exchanger', 'role': 'user'}, {'content': "Answer: C \nExplanation: HCO3 is absorbed with the step of Na+ - H+ exchanger Ref: Ganong's review of medical physiology; 24th edition; page no; 680 Ref of imag :", 'role': 'assistant'}]