An an abbreviation for the name of an element and usually has either one or two letters

the form of energy changes and the total energy increases0l

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

hope it ,

bioteacher101