The answer is; D
The plasticity of rock in the mantle and the convection currents in the region are responsible for tectonic plate movements. The hot molten rock from deep in the mantle rise and is replaced by the cooler rock at the upper mantle. These convections are similar to those of water in a boiling pot. As the tectonic plates move (as they are dragged by these convections) and collide, earthquakes are caused. In addition, at subductions zones (where two plates collide) there occurs high volcanic activity.