Which UV rays reach the skin and contribute to skin damage?

The correct answer identifies that UVA and UVB rays are the ones that penetrate the skin and contribute to skin damage.

UVA rays are known for their ability to penetrate deep into the skin layers, leading to photoaging, DNA damage, and an increased risk of skin cancer. They are present throughout the day and can even penetrate through clouds and glass, making them a constant threat to the skin.

UVB rays, on the other hand, primarily affect the outer layers of the skin. They are responsible for causing sunburn and play a significant role in the development of skin cancer. UVB rays vary in intensity throughout the day and have stronger effects during peak sunlight hours.

While UVC rays are highly energetic and have the potential to cause serious damage, they are mostly absorbed by the ozone layer and do not reach the earth's surface in significant amounts. Similarly, the reference to UVD rays is not applicable as they are not a recognized classification of ultraviolet light.

Thus, UVA and UVB rays are the primary contributors to skin damage, making the selection of UVA and UVB as the correct answer.