Identifying vascular tissues in plant organ diagrams

Steps:

• Analyze diagram 1 for central vascular tissue location and structure indicating phloem.
• Examine diagram 2 for outer bundle arrangement typical of phloem in stems.
• Check diagram 3 for sieve tube presence confirming phloem in root cross-section.
• Verify diagram 4 shows companion cells and no lignified walls, matching phloem.

Why A is correct:

• Phloem transports sugars bidirectionally via sieve tubes, matching all four diagrams' non-lignified, peripheral structures.

Why the others are wrong:

• B misidentifies all as xylem, which has lignified vessels for water transport, unlike the shown tissues.
• C incorrectly alternates xylem and phloem, ignoring consistent phloem features across diagrams.
• D wrongly places phloem only in position 3, overlooking phloem in all positions.

Final answer: A