Which type of radiation from the sun has the greatest potential to harm human skin?

Ultraviolet (UV) rays, is the right answer.

The sun emits rays in an extended spectrum of wavelengths, the maximum of which is not visible to human eyes. The shorter wavelength means that the radiation is more energetic and that it has the greater potential for harm. Therefore, the UV Rays that has a wavelength between 290 and 400 NM, have great potential for harm to humans. Sunburn, Suntan are some of the common impacts of over-exposure of humans to UV. Skin cancer is another disease caused by the UV Rays. Thus, the most harmful sun rays to the human being are the Ultraviolet Rays.