Which of the following is a true statement about tectonic plates?
a. they located in the molten layer beneath the earth first.
b. all tectonic plates are located at the earth's core
c. they're located approximately 10 meters below the surface of the ocean.
d. all of the earths landmass rests on tectonic plates.

I would go with D as it is closest to correct. Every part of the surface of the Earth is a tectonic plate though. The plates vary in thickness, but all of the surface of the Earth is made up of tectonic plates, including the parts under the ocean. Technically, the Earth's landmass does not rest on the tectonic plates, it IS the tectonic plates, but it is the closest to correct here in my opinion.