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 main site of bicarbonate re-absorption is: \nSelect and explain. \nA. Proximal convoluted tubule, B. Distal convoluted tubule, C. Coical collecting duct, D. Medullary collecting duct', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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', 'role': 'assistant'}]