What is the role of keratin in hair?

Keratin plays a vital role in providing strength and structure to hair. It is a fibrous structural protein that is a key component of the hair shaft. The presence of keratin contributes to the hair's durability, resilience, and overall integrity, allowing it to withstand various physical and environmental stresses. This structural aspect is crucial for maintaining the hair's shape and preventing damage such as breakage or frizziness.

Other options relate to different functions that are not as directly associated with keratin. For example, while color in hair is produced by melanin, keratin does not have a role in pigmentation. Moisture retention is primarily managed by lipids and other hydrating substances rather than keratin. Additionally, the regulation of pH within the hair is influenced by the scalp's natural oils and the use of specific hair products, which are unrelated to the function of keratin itself. Thus, the choice that identifies keratin's role in providing strength and structure is the most accurate reflection of its significance in hair health.