Qn:149

At ground level, ozone is a harmful pollutant, but in the stratosphere it shields the Earth from the most biologically harmful radiation emitted by the Sun, radiation in the ultraviolet band of the spectrum.

(A) in the stratosphere
(B) in the stratosphere, in which
(C) it is in the stratosphere in which
(D) in the stratosphere where
(E) it is in the stratosphere and




Official Answer: A