Geologists obtain indirect evidence about earth’s interior by
a. measuring pressure differences at earth’s surface.
b. estimating temperature inside earth.
c. directly looking under the many layers.
d. recording and studying seismic waves.

Geologists obtain indirect evidence about earth's interior by recording and studying seismic waves. The correct option is D. Seismic waves are of two pricipal types. The type P seismic wave goes through solid and liquid while the S type goes through solid only.

The answer is d .recording and studying seismic waves 

Cis correct i think

They both have rock surfaces