Which of the Following Is True of UV Exposure

Multiple Choice

Which of the following is true of UV exposure?

A) UVA radiation is not filtered by the ozone layer and amounts for about 25% of all UV radiation reaching the surface of Earth.
B) Only exposure to UVA is a concern,not exposure to UVB and UVC.
C) UV radiation is potentially harmful and individuals should take appropriate precautions depending on the UV index.
D) UV radiation varies temporally according to the season,local weather conditions,and overhead ozone depletion.