I NEED HELP I WILL CROWN YOU IF YOU ANSWER 1ST AND CORRECT
18)

C

Explanation:

Because It is more detailed about earth layering.

What im trying to say is lava layers.

Either that or D.

Scientists can tell by observing the seismic waves that are recorded all over the surface of the earth from distant earthquakes. The seismic waves are reflected (bounced off) layers of different density, and they are refracted (bent) when they enter layers of different density.

So the answer should be A. Hope it helped

i think it's c. i'm not sure but i think so.