The thickness of the troposphere varies from place to place and from day to day. what influences its thickness

The thickness of the troposphere varies on a daily basis, about 5 miles at the poles and about 11 miles at the equator. As well as this, it becomes thinner in colder weather, so especially the season of winter, due to the air density being at its lowest. So, location on the planet and temperature are two major factors which influence thickness of the troposphere.

D, the answer is letter d. because even though fossil fuels take a very long time to form, they do form in the ground just like coal and others.