What effect does prolonged UV exposure have on skin pigmentation?

Prolonged UV exposure has a significant effect on skin pigmentation, primarily by causing increased melanin production, which results in a tan. Melanin is the pigment responsible for the color of the skin, and its production is a protective response to ultraviolet (UV) radiation. When the skin is exposed to UV rays, the body increases the production of melanin to absorb and dissipate the harmful radiation, which helps to protect the deeper layers of the skin from potential damage such as sunburn or skin cancer.

This tanning response indicates that the skin is attempting to safeguard itself against UV-induced damage. The increased melanin not only darkens the skin tone temporarily but can also lead to long-term changes in pigmentation with repeated exposure, illustrating the skin's adaptive mechanism to UV light. Therefore, the correct answer highlights this crucial physiological response of the skin to UV radiation, emphasizing the protective role of melanin in skin health.