Which type of hair contains true melanin?

The correct answer is dark hair because dark hair contains true melanin, specifically eumelanin, which is the pigment responsible for the dark color. Melanin is produced by melanocytes in the hair follicle and comes in two main types: eumelanin, which can be either black or brown, and pheomelanin, which provides a yellow to red coloration.

In contrast, gray hair results from a lack of pigment, specifically due to a decrease in melanin production as one ages. Blond hair has lower levels of eumelanin compared to dark hair, leading to its lighter appearance, but it still contains some melanin. Red hair derives its color primarily from pheomelanin, which differs from the darker hues contributed by eumelanin in dark hair. Thus, dark hair is the option that indicates the presence of true melanin in significant quantities, making it the correct choice for this question.