Question ID:PT9 S2 Q8 Passage:Most of the ultraviolet radiation reaching the Earth’s atmosphere from the Sun is absorbed by the layer of stratospheric ozone and never reaches the Earth’s surface. Between 1969 and 1986, the layer of stratospheric ozone over North America thinned, decreasing by about 3 percent. Yet, the average level of ultraviolet radiation measured at research stations across North America decreased over the same period. Stem:Which one of the following, if true, best reconciles the apparently discrepant facts described above? Correct Answer Choice:DChoice A:Ultraviolet radiation increases the risk of skin cancer and cataracts; the incidence of skin cancer and cataracts increased substantially between 1969 and 1986. Choice B:Between 1969 and 1986, the layer of stratospheric ozone over Brazil thinned, and the average level of ultraviolet radiation reaching the Earth’s surface in Brazil increased. Choice C:Manufactured chlorine chemicals thin the layer of stratospheric ozone. Choice D:Ozone pollution, which absorbs ultraviolet radiation, increased dramatically between 1969 and 1986. Choice E:Thinning of the layer of stratospheric ozone varies from one part of the world to another and from year to year.