How are glaciers constructive

Glaciers are a destructive force because they can tear down anything in their path and pick up soil and other sediment as the rolls down a hill, BUT they can also constructive, because they can also deposition when they melt and could build up new landforms.
A constructive force is a force that builds up Earth's crust.

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.

Air pollution: “combustion results in gases such as nitrogen oxides, nitrogen dioxide and particulates. the main causes of air pollution include transport, domestic combustion and industrial processes. pollutants from these sources can cause problems in the immediate vicinity and a distance away.”