Assertion (A): Ozone is destroyed by solar radiation in the upper stratosphere. Reason (R): Thinning of the ozone layer allows excessive UV radiations to reach the surface of the earth. (i) Both A and R are correct and R is the correct explanation of A. (ii) Both A and R are correct but R is not the correct explanation of A. (iii) Both A and R are not correct. (iv) A is not correct but R is correct.