Which type of blood cell fights infection and disease?

• A. Platelets
• B. White blood cells
• C. Plasma
• D. Red blood cells

Answer: (B)

White blood cells are the body's defense cells. They circulate in blood and tissues to identify and attack invading organisms like bacteria, viruses, and parasites, helping protect you from infection and disease. Some white blood cells act as first responders, phagocytosing (engulfing) pathogens, while others coordinate or carry out targeted immune responses, such as producing antibodies. In contrast, platelets focus on clotting to stop bleeding, plasma is the liquid that carries blood cells and nutrients, and red blood cells transport oxygen to tissues. So the cell type that fights infection and disease is white blood cells.