The only difference between gray and pigmented hair is that gray hair lacks this.

• A. Melanin
• B. Keratin
• C. Water
• D. Sebum

Answer: (A)

Hair color comes from melanin produced by pigment cells in the hair follicle. As melanin production decreases with age or due to genetics, the hair shaft contains less pigment and appears gray (or white when pigment is absent). The rest of the hair’s structure—keratin, water content, and sebum—remains the same and does not determine color. Some gray hairs may still contain small amounts of melanin, but substantially less than pigmented hairs. Therefore, the presence or absence of melanin is what distinguishes gray hair from pigmented hair.