In looking at a sample of pond water through low power in the microscope, you notice a tiny (0.5 mm) animal busily sweeping small algae cells towards its mouth using whorls of cilia. You can see its complete mouth-tube-anus digestive tract. This animal is :

1.a brachiopod.
2.a ctenophore.
3.a flatworm.
4.a rotifer.

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

u can get stuck if wrong may u pls give mt the optians

explanation: