The correct answer is - D. the rock cycle.
The rock cycle is a process that happens with the interaction between the crust and the mantle layers of the Earth. Where there's suduction zones and the crust from one tectonic plate goes below the other denser one, the crust gets into the mantle and is melted. On the other hand, where we have two tectonic plates moving away from each other the mantle lets material up to fill in the gap, thus creating a new crust. Also the mantle layer is responsible for the volcanic activities which are producing the igneous rocks from the lava, which are the rock type that is the basis for forming the other two types of rocks. This is an ongoing process for hundreds of millions of years.
