The correct option is D All of the above
Just as the glass in a greenhouse holds the sun’s warmth inside, the atmosphere traps the sun’s heat near the earth’s surface and
keeps it warm. This is called the natural greenhouse effect.
If the amount of CO2 in air increases, natural green house balance is disturbed and the atmosphere gets heated. This causes global warming.
There are several ways to reduce global warming e.g. by minimising automobiles, by doing afforestation, by avoiding burning dry leaves, fodders and by avoid smoking. Hence option (d) is the correct answer.