What is the primary effect of UVB rays on the skin?

The primary effect of UVB rays on the skin is melanin production. UVB rays are responsible for stimulating the melanocytes in the skin to produce melanin, which is the pigment that gives skin its color and provides a degree of protection against further UV damage. This process is the body's natural response to UV exposure, resulting in a tanning effect as more melanin is produced.

While other options may involve skin changes, they do not directly relate to the primary biological response to UVB exposure. For example, deep tissue burning primarily results from excessive UV radiation leading to damage in deeper skin layers, which is more characteristic of UVC radiation or prolonged UV exposure rather than a direct effect of UVB. Instant tanning does not accurately describe the process; tanning occurs over a period as melanin accumulates. Fading of the skin, on the other hand, can result from various factors, including sun damage but is not a primary effect of UVB rays. Overall, the key action of UVB rays is to trigger increased melanin production as a protective response.