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: Biochemistry
Which among the following is referred to as alkali reserve of the body? 
Select and explain. 
A. Bicarbonate, B. Carbonic acid, C. Water, D. All of the above
A: Bicarbonate
Answer: A: Bicarbonate 
Explanation: Sodium bicarbonate and carbonic acid are the major buffers of the body, but the concentration of bicarbonate is 20 times higher than carbonic acid. Hence, bicarbonate is known as alkali reserve of the body.