The correct answer is option 2: Calyptrogen.

The root cap is a specialized structure found at the tip of a plant`s root. It is responsible for protecting the delicate growing cells at the root tip as the root pushes through the soil. The root cap is derived from a specific type of tissue called the calyptrogen. This tissue surrounds and protects the root apical meristem, which is responsible for cell division and growth in the roots. The calyptrogen is located just behind the root cap and is involved in the production of the root cap cells. The root cap itself is composed of several layers of cells that constantly slough off as the root pushes through the soil, protecting the root apical meristem from damage.