Rule of law is the basic requirement for peace progress and proeperity of the country

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.

a:

by the combination of an unlimited number of elements

i do not get it   at all