Which of the following is primarily responsible for filtering blood in the lymphatic system?

The spleen is primarily responsible for filtering blood in the lymphatic system. It plays a crucial role in the immune response by removing old and damaged blood cells and pathogens from the bloodstream. The spleen contains white blood cells that help fight infections, and it acts as a reservoir for blood, releasing it into the circulatory system when necessary.

While the thymus is essential for the maturation of T-cells (a type of white blood cell), it does not filter blood. Lymph nodes also play an important role in filtering lymph fluid and facilitating immune responses, but they process lymph rather than blood. Bone marrow is primarily responsible for the production of blood cells, including red blood cells, white blood cells, and platelets, rather than filtering blood. Thus, the spleen stands out as the main organ that filters blood within the lymphatic system.