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
Most impoant buffer system present in the distal convoluted tubule 
Select and explain. 
A. Bicarbonate, B. Phoshate, C. Protein, D. Ammonia
D: Ammonia
Answer: D: Ammonia 
Explanation: Ammonia acts as buffer in DCT and PCT. Ref: Ganong's review of medical physiology; 24th edition; page no: 713