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
Carbonic anhydrase in the kidney tubular cells is known to be associated with: 
Select and explain. 
A. Urea, B. Chloride, C. Bicarbonate ion, D. Carbohydrate
C: Bicarbonate ion
Answer: C: Bicarbonate ion 
Explanation: None