Which of the following is a function of the kidney?

• A. Maintaining an acid-base balance
• B. Digesting carbohydrates
• C. Producing bile
• D. Oxygen transport

Answer: (A)

The kidneys regulate the body's acid-base balance. They adjust the levels of hydrogen ions and bicarbonate in the blood during urine formation, helping keep blood pH in a narrow, healthy range. This balance is crucial for enzyme function and metabolism. Digestion of carbohydrates happens in the digestive tract with enzymes like amylase; bile production is a liver function; oxygen transport is handled by red blood cells. So the kidney’s role in maintaining acid-base balance is the function described.