Which of the following is a type of white blood cell?

• A. Neutrophils
• B. Hemoglobin
• C. Platelets
• D. Plasma

Answer: (A)

White blood cells are the immune system’s defenders, and neutrophils are one of the main types. They are the most abundant white blood cells and act as first responders to infection, engulfing and digesting bacteria and debris through a process called phagocytosis. They’re produced in the bone marrow and circulate in the bloodstream, ready to react when an invader is detected.

The other terms aren’t white blood cells: hemoglobin is the oxygen-carrying protein inside red blood cells; platelets are small fragments that help with blood clotting; plasma is the liquid portion of blood that carries cells and nutrients.