Identifying white blood cells by morphological features

Steps:

• Examine nucleus shape: multi-lobed for neutrophils, kidney-shaped for monocytes, round for lymphocytes.
• Assess cytoplasm: scant and clear in lymphocytes, abundant and grayish in monocytes, granular in neutrophils.
• Note cell size: lymphocytes smallest, monocytes largest, neutrophils medium.
• Match labels X, Y, Z to these traits: X as neutrophil (lobed nucleus), Y as monocyte (large with indented nucleus), Z as lymphocyte (small round nucleus).

Why D is correct:

• Option D matches standard definitions: neutrophils have 3-5 lobed nuclei and fine granules; monocytes have horseshoe nuclei and vacuolated cytoplasm; lymphocytes have high nucleus-to-cytoplasm ratio.

Why the others are wrong:

• A: Misplaces monocyte and neutrophil, ignoring monocyte's larger size and nucleus shape.
• B: Swaps neutrophil and monocyte, contradicting neutrophil's lobed vs. monocyte's indented nucleus.
• C: Incorrectly sequences monocyte first and lymphocyte last, overlooking typical size and nuclear differences.

Final answer: D