What is the primary function of melanin in the hair?

The primary function of melanin in hair is to provide color. Melanin is a natural pigment that is produced by specialized cells in the hair follicle known as melanocytes. There are different types of melanin—eumelanin, which can be either black or brown, and pheomelanin, which is yellow or red. The combination and concentration of these pigments determine the overall color of an individual's hair.

While aspects such as texture and growth rate are important for the hair's overall characteristics, they are influenced by factors such as hair follicle shape and health, rather than melanin. Additionally, melanin does not play a direct role in moisture absorption. Therefore, the correct answer highlights the essential role of melanin as the determinant of hair color.