Which row gives the correct explanation of how the structures of phloem sieve tube elements and xylem vessel elements are linked to their roles as transport systems?
- Aphloem sieve tube elements contain mitochondria to make ATP for the active loading of sucrose into the phloem; xylem vessel elements cell walls are thickened and contain lignin which makes xylem vessels waterproof
- Bphloem sieve tube elements contain no nucleus so that dissolved solutes can move easily through cells; xylem vessel elements end walls between cells are perforated so that water can move easily through xylem vessels
- Cphloem sieve tube elements end walls between cells are perforated so that dissolved solutes can move between cells; xylem vessel elements lignin in cell walls gives strength so that xylem vessels do not collapse due to transpiration pull
- Dphloem sieve tube elements have no end walls between cells so that sucrose solution can move up and down the phloem; xylem vessel elements contain no cytoplasm so that a continuous column of water can move up the xylem vessels