Parenchyma:
Parenchyma cells are simple, unspecialized plant cells that make up the bulk of the plant body. They have thin, flexible primary cell walls that are usually not lignified. The primary function of parenchyma cells is to carry out various metabolic activities such as photosynthesis, storage, and secretion. They are typically found in the outer layers of stems, roots, leaves, and fruits.

Aerenchyma:
Aerenchyma is a specialized type of parenchyma tissue that contains air spaces. These air spaces provide buoyancy to the plant and enable efficient oxygen transport to submerged plant parts. Aerenchyma cells have thin cell walls to facilitate the movement of gases.

Epidermal cells:
Epidermal cells are the outermost layer of cells in plants. They form a protective covering over the plant surface and help reduce water loss through the process of transpiration. Epidermal cells have a thick cuticle layer on their outer surface and often have specialized structures such as trichomes and stomata. The cell walls of epidermal cells are typically thin and flexible.

Collenchyma:
Collenchyma cells are elongated cells with irregularly thickened primary cell walls. These thickened walls are most prominent at the corners of the cells, providing structural support to young and growing plant parts. Collenchyma cells are usually found below the epidermis, in regions of the plant that require flexibility and tensile strength. The cell walls of collenchyma cells are non-lignified, allowing them to stretch and expand as the plant grows.

Correct answer:
In the given question, the correct answer is option 'B' - Collenchyma. Collenchyma cells have thickened walls at the corners and non-lignified cell walls, which provide structural support and flexibility to the plant. These characteristics are not observed in parenchyma, aerenchyma, or epidermal cells.