White blood cells primarily function in which body system?

White blood cells primarily function in which body system?

• A. Lymphatic
• B. Circulatory
• C. Nervous
• D. Digestive

Answer: (A)

White blood cells are the body's defenders, working within the immune system. The lymphatic system is the network where much of this immune activity happens—lymph nodes, spleen, thymus, and lymph fluid host and coordinate immune cells like lymphocytes and macrophages. While white blood cells do travel in the blood, their primary role is to detect, attack, and neutralize pathogens through immune responses that the lymphatic system organizes. The other body systems aren’t where this defense activity is centered—circulation mainly transports, the nervous system handles signaling, and the digestive system processes food.