HELP PLEASEEE How do we know what is inside the Earth? (How do we know the Earth has layers?)

(if you put a random answer for the points i will report)

Scientists know about the layers of the earth by sending sound waves through the earth. Because layers of different densities will allow sound waves to travel through them differently, we can study the sound waves to understand the layers of the earth.

Scientist use special technology to figure out what is inside of the Earth

The correct answer is c. orbital shape. "the angular momentum quantum number l describes the shape of an orbital. it corresponds to each orbital type, i.e. (0,1,2,−1)=(s,p,d,f,g,"