Tectonic activity causes potential energy to build up in the crust. An earthquake occurs when this potential energy is released within the crust. Which statement BEST describes what happens when the energy is released? Select one:

a. It generates seismic waves that spread out in all directions around Earth.

b. It generates heat waves that affect climate changes around Earth.

c. It generates changes in the magnetic field of Earth.

d. It generates changes in the orbiting speed of Earth.