Many scientists suggest that billions of years ago, life on earth began with complex, multicellular organisms because

allowed for the prediction of the properties of missing elements.

very

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