Plant tissues fall into two broad groups: meristematic tissues, whose cells retain the ability to divide, and permanent tissues, whose cells have specialised and lost that ability. This question asks for the defining property of meristematic tissue with respect to cell division and function.

The distinguishing feature is that the cells divide actively and contribute to plant growth. Meristematic cells are small, thin-walled, densely packed, rich in cytoplasm, have prominent nuclei, and typically lack large vacuoles or intercellular spaces — all features that suit continuous mitotic division. Their location determines the kind of growth they drive:

• Apical meristems, at root and shoot tips, cause primary growth — an increase in length/height.
• Lateral meristems (e.g. the cambium), along the sides, cause secondary growth — an increase in girth/thickness.
• Intercalary meristems, at the base of leaves or internodes (common in grasses), help regrowth after grazing or cutting.

The other options describe permanent tissues, not meristem:

• Storing nutrients and maintaining reserves is a role of parenchyma (a permanent ground tissue), not of dividing cells.
• Forming a protective covering across the surface describes epidermal/dermal tissue.
• Transporting water and minerals is the job of xylem (a conducting/vascular tissue).

Only meristematic tissue is defined by ongoing division that fuels growth, so the correct answer is Cells divide actively and contribute to plant growth.