Which organ is part of the lymphatic system?

• A. Heart
• B. Liver
• C. Skin
• D. Lymph node

Answer: (D)

The main idea here is recognizing components that belong to the lymphatic system, which collects excess tissue fluid and supports immune responses. Lymph nodes are small, bean-shaped structures along lymphatic vessels that act as filtering stations for lymph. They trap pathogens and debris and are rich with immune cells like lymphocytes and macrophages that become activated when needed. This is why a lymph node is representative of the lymphatic system.

The other organs listed don’t serve as primary lymphatic organs: the heart belongs to the circulatory system, pumping blood; the liver is a metabolic and immune organ but not a central part of the lymphatic network; the skin is part of the integumentary system with immune roles, but it isn’t a primary lymphatic organ.