How does the lymphatic system contribute to the immune system?

• A. It stores vitamins.
• B. It regulates heart rate.
• C. It forms part of the immune system that defends against disease and infection.
• D. It filters air.

Answer: (C)

The lymphatic system’s role in immune defense is to house and transport immune cells and to provide sites where immune responses are activated. Lymph nodes act as filters where pathogens are trapped and antigen-presenting cells like macrophages and dendritic cells show them to T cells, helping to start adaptive immunity. The spleen helps remove pathogens from the blood, and the thymus is where T cells mature. This network of vessels and lymphoid organs allows immune cells to patrol the body, recognize invaders, and coordinate responses to eliminate infection.

Other options don’t fit because storing vitamins isn’t a primary lymphatic function (vitamin storage is handled by other organs and tissues), regulating heart rate is controlled by the nervous system and hormones, and filtering air is a function of the respiratory system.