Final answer:
The part of the hair beneath the epidermis is the hair root, the living component of hair that is responsible for hair growth and anchored within the hair follicle. The correct option is 4) Root sheath
Step-by-step explanation:
The part of the hair located below the surface of the epidermis is known as the hair root. The hair root is a critical component of hair anchored in the follicle, lying beneath the surface of the skin, and it ends at the hair bulb in the dermis.
Contrary to the external hair shaft, which is composed entirely of dead, keratinized cells and is visible above the skin surface, the hair root includes living cells that are engaged in the production of new hair.
Within the structure of the hair follicle, several layers are involved, such as the medulla which forms the central core, the cortex that provides shape and texture, and the cuticle which is the outermost protective layer.
The most accurate answer to the question is the hair root, which is the only living part of the hair and where hair growth begins. The correct option is 4) Root sheath