[Figure: Three white blood cells. A – a cell with a nucleus of three lobes joined by thin strands and fine granules in the cytoplasm. B – a cell with a bilobed nucleus (two rounded lobes joined at the base, U-shaped) and granules scattered in the cyt…

Answer: A = Neutrophil, B = Eosinophil, C = Monocyte.

1. A – Neutrophil (granulocyte with a 3–5 lobed nucleus and fine granules): the most numerous WBCs (60–70%); actively phagocytic, they engulf and destroy bacteria and form the first line of cellular defence at sites of infection.
2. B – Eosinophil (acidophil) (granulocyte with a bilobed nucleus; granules take up the acidic stain eosin): 2–3% of WBCs; they fight parasitic (worm) infections, take part in allergic reactions and reduce their effect by destroying histamine (antihistamine action), and phagocytose antigen–antibody complexes.
3. C – Monocyte (largest agranulocyte with a kidney-shaped nucleus): phagocytic; they migrate into tissues and become macrophages that engulf bacteria, dead cells and debris, and help in presenting antigens.