Which type of plant tissue is being described by the given statements?

1. It consists of long, narrow cells with thick and lignified cell walls having a few or numerous pits.
2. They are dead and without protoplasts.
3. On the basis of variation in form, structure, origin and development, it may be either fibres or sclereids.
4. It provides mechanical support to organs.

The given statements are associated with sclerenchyma plant tissue. Sclerenchyma cells are strengthening tissue in a plant, formed from cells with thickened, typically lignified, walls. Such cells occur in many different shapes and sizes, but two main types occur: fibres and sclereids. Fibres are greatly elongated cells whose long, tapering ends interlock, thus providing maximum support to a plant. They can be found almost anywhere in the plant body, including the stem, the roots, and the vascular bundles in leaves. Sclereids are extremely variable in shape and are present in various tissues of the plant such as the periderm, cortex, pith, xylem, and phloem.