Which function describes kidneys?

• A. Break down protein, filter toxins and poisons, and form urine wastes
• B. Pumps blood and oxygen
• C. Secretes insulin
• D. Digest carbohydrates

Answer: (A)

Kidneys mainly filter waste from the blood and form urine, while helping regulate fluids, electrolytes, and acid-base balance. The option that emphasizes filtering toxins and forming urine wastes best fits this role, since removing waste products and producing urine are core kidney functions. It’s true that breaking down protein isn’t a kidney task—that happens mainly in the liver and digestive system—but the idea of filtering waste and producing urine captures what the kidneys do.

The other options describe functions of different organs: pumping blood and oxygen is the responsibility of the heart and lungs; secreting insulin is a pancreatic function; and digesting carbohydrates is part of the digestive system.