What system does lymph primarily support?

The lymphatic system primarily supports the immune system. Its main functions include the transportation of lymph, a fluid that contains infection-fighting white blood cells, throughout the body. The lymphatic vessels collect lymph from tissues, which is then processed through lymph nodes. These nodes are critical for filtering out harmful pathogens and facilitating an immune response.

Additionally, the lymphatic system plays a key role in maintaining fluid balance in the body and absorbing fats from the digestive system, but its primary relationship is with the immune system. By helping to produce and transport lymphocytes, which are crucial for the body’s defense mechanisms, the lymphatic system is integral to protecting the body against infections and diseases. This is why the correct answer is C, as the lymphatic system's functions are most directly aligned with supporting the immune system.