Which organ filters blood, stores blood cells, and helps fight infection?

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

Answer: (B)

The spleen uniquely fits all three roles: it filters the bloodstream, acts as a reservoir by storing blood and platelets, and contributes to immune defense by housing lymphocytes and helping to mount responses to infections. Macrophages in the spleen remove bacteria and debris from the blood, while the white pulp area participates in immune activity. Other organs have different primary tasks—kidneys filter blood to produce urine, liver processes nutrients and detoxifies, and the pancreas handles digestion and hormone release—so they don’t match all three functions together as the spleen does.