What part of the skin do hair and follicles belong to?

Hair and follicles are primarily associated with the pilosebaceous unit, which is made up of the hair follicle, the hair itself, sebaceous glands, and sometimes the arrector pili muscle. This unit is located in the dermis layer of the skin, where the follicles reside, and it plays a crucial role in hair growth and the maintenance of healthy skin.

The epidermis is the outer layer of skin and does not contain hair follicles, while the dermal papillae are small, nipple-like projections at the surface of the dermis that provide nutrients to the hair follicles, but they are not the main components of the pilosebaceous unit itself. Thus, the choice that accurately refers to both hair and follicles belonging to the epidermis and the pilosebaceous unit is correct, highlighting the integral relationship these structures have within the skin.