What is the main function of lymph in the body?

The primary role of lymph in the body is to play a critical part in the immune system, particularly through the processes of filtration and phagocytosis. Lymph is a clear fluid that circulates through the lymphatic system, transporting various substances, including white blood cells, which are essential for immune defense.

During filtration, lymph fluid passes through lymph nodes where it is filtered to remove pathogens, cellular debris, and other harmful substances. This filtration process helps in identifying and eliminating infections and other dangers to the body. Phagocytosis is the mechanism by which certain immune cells, such as macrophages, engulf and destroy these pathogens and debris, further protecting the body from disease.

While the other choices mention important physiological processes, they do not accurately reflect the central function of lymph. For instance, lymph does not primarily produce hormones or transport nutrients like blood does. Although lymph aids in the absorption and circulation of fats, especially from the digestive system, its foremost function is tied to immune response and waste removal, which aligns with the emphasis on filtration and phagocytosis.