Which rays penetrate deeper into the subcutaneous layer?

The correct choice is UVA rays, which are known for their ability to penetrate deeper into the skin, reaching the dermal and subcutaneous layers. UVA rays have a longer wavelength compared to UVB and UVC rays, allowing them to pass through the upper layers of the skin more effectively. This deeper penetration can lead to skin aging and increased risk of skin cancer.

In contrast, UVB rays primarily affect the outer layer of the skin (the epidermis), causing sunburn and playing a significant role in the development of skin cancer. UVC rays are mostly absorbed by the ozone layer and do not generally reach the Earth’s surface, thereby having minimal impact on the skin. Infrared rays, while they can penetrate into the skin and create a warming sensation, do not have the same direct effects on skin cells as UVA rays do, which is why UVA is recognized for deeper infiltration in terms of skin damage and photobiological effects.