Translocation occurs in phloem tissue of leaf veins

Steps:

• Identify the diagram as a leaf cross-section showing vascular bundles.
• Recall that translocation transports sugars (sucrose) and amino acids from leaves to other plant parts.
• Locate the vascular tissues: xylem for water/minerals upward, phloem for organic solutes bidirectionally.
• Match translocation pathway to phloem sieve tubes in the vein.

Why B is correct:

• Phloem conducts translocation via mass flow of sucrose and amino acids in sieve tubes, as defined by the pressure-flow hypothesis.

Why the others are wrong:

• A: Xylem transports water and minerals, not sugars or amino acids.
• C: Mesophyll cells photosynthesize but do not translocate solutes.
• D: Epidermis provides protection, lacking vascular transport.

Final answer: B