Organelle distribution in plant vascular tissues

Steps:

• Recall companion cells contain organelles like endoplasmic reticulum and nucleus for supporting sieve tubes.
• Note phloem sieve tube elements lack a nucleus but rely on companion cells.
• Identify xylem vessel elements as dead cells without cytoplasm or organelles.
• Match diagram labels to these features for correct associations.

Why A is correct:

• Companion cells possess endoplasmic reticulum; sieve tube elements lack a nucleus; xylem vessels lack cytoplasm, per plant cell specialization definitions.

Why the others are wrong:

• B incorrectly assigns endoplasmic reticulum and nucleus to sieve tubes and vessels, which lack them.
• C wrongly places mitochondria and nucleus in sieve tubes and vessels, ignoring their enucleate/dead nature.
• D misattributes vacuole and "no" features to phloem cells and tube elements without accurate ties.

Final answer: A