Question

why are hairs are black not red or pink.

Answer 1

Hair color is the pigmentation of hair follicles due to two types of melanin: eumelanin and pheomelanin.
Generally, if more eumelanin is present, the color of the hair is darker; if less eumelanin is present, the hair is lighter.
Levels of melanin can vary over time causing a person's hair color to change, and it is possible to have hair follicles of more than one color on the same person.
Both of these proteins don't form blue, green, while yellow (Blond) and red is possible.

Answer 2

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