Which type of melanin is dark brown to black in color?

Eumelanin is the type of melanin primarily responsible for darker shades of pigmentation in hair, skin, and eyes, presenting as dark brown to black. This pigment plays a critical role in absorbing harmful UV radiation, thus offering some protection against sun damage. The production of eumelanin occurs in melanin-producing cells called melanocytes, where the enzyme tyrosinase catalyzes the conversion of the amino acid tyrosine into melanin.

In contrast, pheomelanin is lighter in color, producing yellow to red pigments and is often found in lighter hair shades and in individuals with red or blonde hair. Tyrosinase is an enzyme, not a pigment, and serves as a crucial component in the melanin synthesis pathway but does not possess color itself. Keratin is a structural protein that plays a key role in the strength and resilience of skin and hair but is unrelated to pigmentation. Thus, eumelanin stands out as the correct answer due to its characteristic color and role in pigmentation.