The answer is; Wind
They drive atmospheric circulation. The sun does not heat the earth evenly. The parts that are heated up more form the low-pressure systems where air masses move in from high-pressure systems to form winds. These air masses are also deflected by Coriolis effect caused by earth’s rotation.
<span>Erosion by rivers is a main valley-forming
process; other processes, such as movement of the earth's crust and
glaciers, also have an important part in some cases. The rate at which a
river deepens its valley depends on several factors.</span>
I just did this lesson, and the answer is B.
I hope this helps you!
-Mikayla
interesting, the moon, the earth, the other things in reality is only a pratice for the real thing....