Final answer:
The term 'epidermal' relates to the epidermis layer of the skin, which is the outermost layer and serves to protect the body.
Step-by-step explanation:
The correct answer to the question 'What is epidermal?' is C. Relating to the epidermis layer of the skin. The epidermis is the outermost layer of skin in mammals, which is relatively thin and composed of keratin-filled cells with no blood supply. The primary function of the epidermis is to act as a barrier to water and to invasion by pathogens. It is distinct from the dermis, which is thicker and contains structures like blood vessels, sweat glands, hair follicles, and sebaceous glands, and the hypodermis or subcutaneous tissue that primarily consists of fat and connective tissue.