Which is a major function of the kidneys?

• A. Elimination of nitrogenous wastes & other toxics
• B. Production of antibodies
• C. Oxygen transport in blood
• D. Digestion of carbohydrates

Answer: (A)

The kidneys’ primary role is filtering blood to remove waste products and toxins, forming urine as a way to excrete them. They continually process the blood to eliminate nitrogenous wastes like urea and creatinine, while also balancing fluids, electrolytes, and acid-base status. This waste-elimination function is what keeps the body's internal environment stable and free of toxic buildup, and it can also involve regulating blood pressure and producing hormones that influence red blood cell production and vitamin D activation.

The other options fall outside the kidneys’ main job. Antibody production is a function of the immune system, primarily B cells. Oxygen transport in the blood is handled by hemoglobin in red blood cells. Digestion of carbohydrates occurs in the digestive tract with enzymes from the mouth to the small intestine and pancreas. Therefore, the elimination of nitrogenous wastes and other toxins is the best choice.