Tectonic plates move because of the flow of heat inside the Earth. Deep in the asthenosphere, there is a convection current—that's when heated things rise and cooled things fall. Since the asthenosphere is not quite liquid rock, convection currents move rock very slowly. Where the crust is thin, the heated rock may rise. This usually happens in the middle of an ocean, creating an ocean basin. Where the crust is thick, like under a continent, rock sinks deeper into the mantle. When tectonic plates move, they rub against each other, causing great stress on the rock. When rock is pushed together, the pressure is called compression. When rock is stretched apart, it's called tension. At points of tension, like under the ocean, magma may come to the surface. At points of compression, layers of rock may bend upward, downward or break entirely. How does convection cause tectonic plates to move? A Convection keeps the plates thin enough to move. B Convection makes the plates solid enough to move. C The rising heat of convection currents moves the almost-liquid rocks. D The pressure of convection bends rocks until they break completely.