What is the function of the cortex in hair?

The cortex of the hair is a critical layer located between the cuticle (outer layer) and the medulla (inner core). Its primary function is to provide strength and color to the hair. The cortical cells contain the majority of the hair's melanin, which is responsible for the hair's natural color. Additionally, the structure of the cortex plays a significant role in the hair's tensile strength and elasticity, allowing it to withstand various styling and environmental factors.

While the hair's color is determined by the melanin present in the cortex, its strength originates from the structural composition of the cortex, which includes long chains of keratin proteins. This is why the answer focuses on the cortex’s role in both the strength and color of hair. Other options might relate to characteristics that are influenced by the cortex, but they do not address its primary functions as accurately.