Which organ filters blood?

• A. Liver
• B. Kidneys
• C. Spleen
• D. Bone marrow

Answer: (C)

The kidneys are the organs that filter blood. They receive blood, filter it through the glomeruli to remove waste products and excess substances, and then regulate fluid and electrolyte balance to form urine. This filtration is a key way the body cleans the blood and maintains homeostasis. The spleen helps remove old red blood cells and supports immune functions, but it does not filter blood to form urine. The liver detoxifies chemicals and metabolizes substances, while bone marrow produces blood cells. So, the organ specialized for filtering blood is the kidneys.