Which layers make up the hair shaft?

The hair shaft is composed of three primary layers: the cuticle, cortex, and medulla.

The cuticle is the outermost layer, consisting of overlapping scale-like cells that protect the inner layers of the hair. This layer plays a key role in the overall appearance and health of the hair, as it influences shine and smoothness.

Beneath the cuticle is the cortex, which is the middle layer and contains fibrous proteins and melanin, the pigment responsible for hair color. The cortex is crucial for the hair's strength, texture, and elasticity. It also determines the hair's ability to hold styles and withstand chemical processing.

Finally, the medulla is the innermost layer of the hair shaft. While not present in all hair types, when it is present, it consists of loosely packed cells and air spaces, contributing to the overall structure of the hair.

In contrast to this correct option, the other choices incorrectly include terms such as "follicle" which refers to the hair's growth unit, rather than layers of the hair itself. "Keratin" is a protein that makes up the hair but does not describe a specific layer, and "porosity," "elasticity," and "density" are properties