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
The main site of bicarbonate re-absorption is: 
Select and explain. 
A. Proximal convoluted tubule, B. Distal convoluted tubule, C. Coical collecting duct, D. Medullary collecting duct
A: Proximal convoluted tubule
Answer: A: Proximal convoluted tubule 
Explanation: Proximal convoluted tubule is the main site of bicarbonate absorption. About 80 to 90 percent of bicarbonate re-absorption occurs in the proximal tubule. Ref:Textbook of Medical Physiology By Guyton, 10th Edition, Page 353