Mature RBCs lack nucleus and organelles, enabling only basic transport

Steps:

• Recall mature red blood cells (RBCs) eject their nucleus and most organelles during maturation to maximize space for hemoglobin.
• Identify processes requiring cellular machinery: division needs nucleus; phagocytosis needs lysosomes and cytoskeleton; protein synthesis needs ribosomes.
• Note RBCs retain plasma membrane with ion pumps for active transport, powered by glycolysis.
• Eliminate options needing absent structures, leaving active transport as feasible.

Why A is correct:

• Mature RBCs use active transport via Na+/K+ ATPase pumps to maintain ion gradients essential for shape and function, relying on anaerobic glycolysis for ATP.

Why the others are wrong:

• B: Lacks nucleus, preventing DNA replication and mitosis.
• C: No lysosomes or phagocytic apparatus for engulfing particles.
• D: No ribosomes, so cannot synthesize proteins.

Final answer: A