From where do autotrophs obtain their energy? Other organisms
O From fertilizers
Other decaying organisms
O The sun

the answer will be a) proteins i believe

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