The correct option is C Increase in UV radiation reaching the earth
Global warming refers to the gradual increase in Earth's average temperature due to increased levels of greenhouse gases such as CO2, CFCs, and other pollutants.
The greenhouse gases trap Earth's heat and, therefore, the amount of heat inside Eath's atmosphere increases causing a warming effect.
The impact of global warming includes a rise in global surface temperature, changes in weather patterns, rise in sea-level and melting of glaciers.
Increase in UV radiations reaching the Earth's surface is caused due to the depletion of ozone layer. This is generally due to the excessive emission of chlorofluorocarbons (CFC), i.e., a class of pollutants.