. A mature sieve tube differs from a vessel

Best Answer

Explanation :

• A mature sieve tube is a stack of vertical cells and its lateral walls have perforated sieve plates because it serves as phloem’s main conducting element.
• It does not have lignin in its wall.
• And they retain protoplast during differentiation but nucleus is absent.
• While vessels are dead elements of xylem that conducts water. It lacks nucleus and cytoplasm.
• Vessel’s secondary walls are thick because of lignin deposition.

Final Answer :

Hence, the correct option is B, i.e. Absence of lignified walls.