In botanical terms, the cortex of a plant is the region found between the epidermis and the stele. Therefore, the correct answer is:

Option C: Epidermis and stele.

To clarify:

• Epidermis: This is the outermost layer of cells in the plant stem and root. It serves as a protective barrier against the external environment.
• Stele: This is the central part of the root or stem, containing the vascular tissue (xylem and phloem), pith, and often a pericycle. The stele is located inside the endodermis.

The cortex lies between these two layers, functioning mainly in storage and transport of nutrients and water. It is composed primarily of parenchyma cells and is a significant part of the root and stem where it often stores starch.

The other options refer to different parts of the plant anatomy:

• Option A: "Endodermis and pith" - The pith is located in the center of the stem, surrounded by the vascular tissue, which is inside the endodermis. The cortex is not between these two.
• Option B: "Endodermis and vascular bundle" - The endodermis is a single layer of cells forming a boundary between the cortex and the stele; it doesn't define the boundaries of the cortex.
• Option D: "Pericycle and endodermis" - The pericycle is a layer of cells found just inside the endodermis, and it is part of the stele. This option does not correctly describe the position of the cortex.

Thus, Option C is the most accurate in describing the location of the cortex in a plant.