The spleen is in what organ system?

The spleen is a part of the lymphatic system, which is responsible for filtering blood, removing damaged blood cells, and supporting immune function. The spleen contains lymphocytes that help fight infections and regulate the immune response.

A. Nervous: The nervous system includes the brain, spinal cord, and nerves, unrelated to immune function.

B. Endocrine: The endocrine system regulates hormones through glands like the thyroid and pancreas, not directly involved with blood filtration or immune cell production.

C. Digestive: While the spleen is located near digestive organs, it does not play a role in digestion.

Thus, the correct answer is D. Lymphatic.