Global warming is mainly due to the increase of: methane and CO2 in atmosphere

The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. The effect of this is global warming. Global warming is due to the increase of greenhouse gases like methane and CO2 in the atmosphere. Methane and carbon dioxide have a major contribution to global warming. Hence, option B is correct.