Concept:Mature sclerenchyma cells are dead cells with thick, lignified secondary walls that provide mechanical support to plants.
Explanation:Sclerenchyma is a plant support tissue composed of hard, woody cells.
Mature sclerenchyma cells are typically dead, meaning they lack living protoplasm.
Their secondary cell walls are heavily thickened with lignin, a complex polymer that makes them rigid and non‑stretchable.
These cells are found in non‑growing regions like bark, mature stems, seed coats, and some fruits (e.g., pear).
There are two main types: fibres (long, slender) and sclereids (stone cells).
Unlike parenchyma (living thin‑walled) and collenchyma (living with uneven walls), sclerenchyma provides permanent structural support.
The key features are lignified walls and dead cells at maturity.
Answer:D. lignified wall and are dead
