Explanation:

The ozone layer, primarily located in the stratosphere (about $10$ to $50 \text{ km}$ above Earth's surface), absorbs most of the Sun's harmful ultraviolet (UV) radiation (UV-B and UV-C), protecting life. Option (2) Methane is a greenhouse gas, not a UV shield. Option (3) Tropospheric ozone is a pollutant, harmful to health, and does not block significant UV radiation from space. Option (4) Chlorofluorocarbons (CFCs) are chemicals that deplete the stratospheric ozone layer, thereby *reducing* protection from UV radiation.