The earth’s internal source provides the energy for our dynamic planet, providing it with the driving force for on-going disastrous events such as earthquakes and volcanic eruptions and for plate-tectonic motion.
a).heat
b).metallic
c).magnetic
d).gravity

A). Heat

Explanation:

Inside the Earth, the primordial heat left from the formation of Earth and the decay of radioactive isotopes in the crust and the mantle are the sources of flow of heat. This interior source of heat is responsible for the motion of the plates which leads to Earthquakes and volcanic eruptions. Internal heat is also used as a source of energy - geothermal energy for heating and cooking.

Thus, the Earth’s internal heat source provides the energy for our dynamic planet, providing it with the driving force for on-going disastrous events such as earthquakes and volcanic eruptions and for plate-tectonic motion.

i think the answer would be b

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers