A is a set of statements about the mechanisms underlying a behavior. postulate

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

it is because according to the process , scientific inquiry is a process with many steps because each step occurs to the scientist and if you just skip a step there would be no steps to scientific inquiry.