Which is a primary function of the lymphatic system?

• A. Movement of lymph and protection against disease
• B. Gas exchange
• C. Mineral storage
• D. Digestion

Answer: (A)

The main idea being tested is that the lymphatic system moves lymph and defends the body against infection. Lymph is the fluid that leaks from tissues and is collected by lymphatic vessels, then filtered through lymph nodes where immune cells monitor for pathogens and mount responses. This network also helps return fluid to the bloodstream, supporting tissue fluid balance. Movement of lymph is powered by muscle contractions and valves in the vessels, not by the heart. Because of this focus on fluid movement and immune protection, this option best describes the primary role of the lymphatic system. Gas exchange happens in the lungs, mineral storage in bones, and digestion in the digestive tract.