Which statement best describes arteries?

A. Transporting dietary fats:The lymphatic system absorbs fats and fat-soluble vitamins from the digestive tract through specialized lymphatic vessels called lacteals. This is an important function that complements nutrient absorption and delivery to the bloodstream.

B. Draining excess interstitial fluid:Lymphatic vessels collect fluid that leaks from blood capillaries into tissues and return it to the circulatory system. This prevents edema and maintains fluid balance, making it a key function of the lymphatic system.

C. Transporting respiratory gases:Transport of oxygen and carbon dioxide is the primary role of the cardiovascular system, not the lymphatic system. Lymph does not carry respiratory gases, so this is not a function of lymphatic vessels.

D. Carrying out immune responses:The lymphatic system supports immune function by housing lymphocytes, filtering lymph through lymph nodes, and facilitating antigen detection. This makes immune defense a central role of the lymphatic system.

A. Can kill cancer cells before the immune system is activated:NK cells are part of the innate immune system and can recognize and destroy virus-infected or cancerous cells without prior sensitization. They provide a rapid, non-specific defense before adaptive immunity is engaged.

B. Are a type of phagocyte:NK cells do not engulf pathogens like phagocytes; instead, they induce apoptosis in target cells by releasing cytotoxic granules. Their mechanism of action is different from phagocytosis.

C. Are also called cytotoxic T cells:Cytotoxic T cells are part of the adaptive immune system and require antigen presentation for activation. NK cells are distinct and act independently of antigen-specific activation.

D. Are cells of the adaptive immune system:NK cells are components of innate immunity, providing immediate defense against abnormal cells. They do not rely on prior exposure to specific antigens, unlike adaptive immune cells.