Final answer:
Melanocytes are responsible for producing melanin, which is the pigment that gives color to the skin. When exposed to UV-B radiation, melanocytes increase melanin production as a defense mechanism, resulting in hyperpigmentation.
Step-by-step explanation:
Melanocytes are responsible for skin pigmentation. They produce and distribute melanin, which is the pigment that gives color to the skin, hair, and eyes. When the skin is exposed to UV-B radiation, melanocytes increase the production of melanin as a defense mechanism to protect the underlying living cells. This increased production of melanin results in hyperpigmentation, which is a darkening of the skin.