The correct answer is option A, that is, transport fluid.
The lymphatic system refers to a network of organs and tissues, which helps in getting rid of the body wastes, toxins, and other undesired elements. However, the main activity of the lymphatic system is to transport lymph, that is, a fluid comprising infection-fighting white blood cells, all through the body.
The lymphatic system mainly comprises of lymphatic vessels that are identical to the circulatory system's capillaries and veins. The vessels are associated with lymph nodes, where the filtration of lymph is done. The adenoids, tonsils, thymus, and spleen are all the components of the lymphatic system.