Assertion (A): Ozone layer protects the surface of the Earth from harmful UV radiations. Reason (R): Chlorofluorocarbons (CFCs) are responsible for depletion of ozone layer.

Assertion (A) is true because the ozone layer ($O_3$) present at the higher levels of the atmosphere shields the Earth's surface by absorbing highly damaging ultraviolet (UV) radiation from the Sun, preventing conditions like skin cancer in human beings. Reason (R) is also true because synthetic chemicals like chlorofluorocarbons (CFCs), used as refrigerants and in fire extinguishers, are responsible for the sharp depletion of the ozone layer. However, the fact that CFCs deplete the ozone layer (Reason) does not explain why or how the ozone layer protects the Earth from UV radiation (Assertion). Therefore, both statements are true, but the Reason is not the correct explanation of the Assertion.