What is the main characteristic of UVC rays?

The main characteristic of UVC rays is that they are absorbed by the stratum corneum. UVC rays have the shortest wavelength and are primarily absorbed by the outermost layer of the skin, which is the stratum corneum. This absorption means that UVC rays do not penetrate deeper into the skin layers, making them less likely to lead to long-term skin damage compared to other types of UV rays, such as UVA and UVB.

In the context of the other choices, while UVC rays can have harmful effects, they do not penetrate to the basal layer, which is characteristic of other UV rays. They are not primarily linked to skin aging, as that is more associated with UVA rays that can penetrate deeper into the skin. Additionally, immediate burning sensations are more related to UVB rays, which are known for causing sunburns, rather than UVC rays that are largely filtered out by the atmosphere and do not usually reach the Earth's surface. Thus, the defining characteristic of UVC rays relates to their absorption by the stratum corneum.