Plant phloem cells retain organelles for function

Steps:

• Identify phloem components: sieve tubes for sugar transport, supported by companion cells.
• Note sieve tube elements mature without nucleus, cytoplasm, or mitochondria to allow flow.
• Confirm companion cells stay alive with full organelles to nourish sieve tubes.
• Contrast with xylem: vessel elements die at maturity, becoming hollow conduits.

Why A is correct:

• Companion cells are nucleated, living parenchyma cells containing cytoplasm, mitochondria, and nucleus per plant cell biology definitions.

Why the others are wrong:

• B: Sieve tubes form from fused sieve tube elements that lack nucleus, cytoplasm, and organelles.
• C: Phloem sieve tube elements lose cytoplasm, mitochondria, and nucleus during maturation.
• D: Xylem vessel elements are dead, lignified tubes without cytoplasm, mitochondria, or nucleus.

Final answer: A