Which organ filters blood and supports immune responses within the lymphatic system?

• A. Spleen
• B. Liver
• C. Pancreas
• D. Kidneys

Answer: (A)

The spleen stands out because it serves as a blood-filtering and immune-activating organ within the lymphatic system. It screens the bloodstream, removing old or damaged red blood cells and pathogens, while also housing lymphocytes in areas called white pulp. Those lymphocytes mount immune responses, producing antibodies and helping defend against infections. This dual role—filtering blood and supporting immune activity—is what makes the spleen the best answer.

The other organs have different main duties: the liver handles metabolism and detoxification, the pancreas focuses on digestion and blood sugar regulation, and the kidneys filter blood to form urine and manage fluid balance. They don’t play the primary, direct role in immune surveillance within the lymphatic system like the spleen does.