Answer:

The correct answer is option 'B' - sclerenchyma.

Sclerenchyma is a type of plant tissue that provides mechanical support and protection to the plant. It is characterized by cells with evenly thickened, hard, and lignified walls. These walls are made up of a substance called lignin, which makes them rigid and tough.

Characteristics of Sclerenchyma Cells:
- Evenly thickened walls: Sclerenchyma cells have walls that are uniformly thickened throughout. This thickening provides strength and support to the plant.
- Hard and lignified walls: The walls of sclerenchyma cells are hardened and reinforced with lignin. Lignin is a complex polymer that adds rigidity and resistance to these cells.
- Lack of protoplasts: Mature sclerenchyma cells are dead and lack protoplasts, which are the living contents of plant cells. The absence of protoplasts allows the cells to be fully filled with lignin, making them rigid and inelastic.
- Lack of intercellular spaces: Sclerenchyma cells are closely packed together, leaving little to no intercellular spaces. This arrangement further enhances their strength and support.

Functions of Sclerenchyma Cells:
- Mechanical support: The thickened and lignified walls of sclerenchyma cells provide strength and support to the plant. They enable the plant to stand upright and resist mechanical stress, such as wind or gravity.
- Protection: Sclerenchyma cells can also act as a protective barrier. For example, in the case of seed coats, the hard and tough sclerenchyma cells prevent damage to the developing embryo.
- Conductivity: In some plants, sclerenchyma cells can also aid in the transport of water and nutrients. They may form specialized structures, such as fibers or sclereids, that facilitate the movement of fluids within the plant.

Examples of Sclerenchyma Cells:
- Fibers: Sclerenchyma fibers are long, slender cells that are commonly found in the stems, leaves, and vascular tissues of plants. They provide structural support and are responsible for the strength and flexibility of plant parts.
- Sclereids: Sclereids, also known as stone cells, are compact and irregularly shaped sclerenchyma cells. They are found in various plant organs, such as the seed coats of nuts and the gritty texture of pears. Sclereids provide mechanical protection and can also contribute to the dispersal of seeds.

In conclusion, cells with evenly thickened, hard, and lignified walls are characteristic of sclerenchyma tissue. These cells provide mechanical support, protection, and sometimes even aid in the transport of fluids within the plant.