Sclerenchyma, in plants, support tissue composed of any of various kinds of hard woody cells. Mature sclerenchyma cells are usually dead cells that have heavily thickened secondary walls containing lignin. The cells are rigid and nonstretchable and are usually found in nongrowing regions of plant bodies, such as the bark or mature stems. Sclerenchyma is one of the three types of ground, or fundamental, tissue in plants; the other two types are parenchyma(living thin-walled tissue) and collenchyma (living support tissue with irregular walls). Sclerenchyma cells occur in many different shapes and sizes, but two main types occur: fibres and sclereids.

Answer:

The correct answer is option D, Sclerenchyma.

Sclerenchyma:
Sclerenchyma is a type of plant tissue that provides structural support to the plant. It is characterized by the presence of thick, lignified cell walls, which make it hard and rigid. It is mainly composed of dead cells that are no longer involved in metabolic activities.

Features of Sclerenchyma Cells:
The cells of sclerenchyma are long, pointed, and have thick walls. These walls are heavily fortified with lignin, a complex polymer that provides strength and rigidity to the cells. The cells are dead at maturity and lack protoplasts, making them resistant to decay.

Types of Sclerenchyma Cells:
There are two main types of sclerenchyma cells based on their shape and arrangement:

1. Fibers: Fiber cells are elongated and occur in bundles. They are characterized by their pointed ends and thick walls. Fibers provide mechanical support to the plant, especially in tissues like the vascular bundles, stems, and leaves.

2. Sclereids: Sclereid cells are irregularly shaped and occur singly or in small groups. They can be found in various plant organs, such as the seed coats, fruit walls, and the hard shells of nuts. Sclereids provide mechanical protection and support to the plant.

Function of Sclerenchyma:
Sclerenchyma cells play a crucial role in providing strength and support to the plant. They help in maintaining the rigidity of plant organs, preventing them from collapsing or wilting. Sclerenchyma tissues also contribute to the protection of delicate plant parts by forming hard coverings or layers.

Conclusion:
In summary, the hard, lignified, thick-walled, long and pointed cells described in the question are characteristic of sclerenchyma cells. These cells provide structural support and protection to the plant body.