Is this investigation a controlled experiment or an observational study? Explain your answer.

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.

that is true   : ) hope this you

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