(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A), as CFCs cause ozone depletion but do not explain how ozone protects Earth from UV radiation.
Both statements are independently true facts. The Assertion states ozone's protective role (blocking UV rays), while the Reason states CFCs deplete ozone. However, the Reason explains a cause of depletion, not the mechanism by which ozone protects Earth — so it does not correctly explain the Assertion. Hence option (B) is correct.