A lengthwise section of hair reveals cuticle scales that overlap. Each cuticle scale is attached to what?

The correct choice is the cortex. The cortex is the middle layer of the hair shaft and plays a crucial role in providing strength, color, and texture to the hair. It consists of long, keratinized cells and is where the majority of the hair's properties are determined.

The cuticle, which is the outermost layer of the hair, is made up of overlapping scale-like cells that protect the inner layers. However, while cuticle scales overlap and can be observed when looking at hair under a microscope, they are not attached to the cuticle itself but rather linked to the cortex beneath.

The medulla, often found in thicker hair strands, is the innermost layer and its presence isn’t always significant in all hair types. The follicle, on the other hand, is the structure located beneath the skin and responsible for hair growth, but it does not form a part of the hair shaft itself.

Understanding these layers and their functions is vital in the field of hair design and care, particularly when assessing hair health and deciding on treatment methods.