Answer: C. subduction zones along convergent plate boundaries
The oceanic lithosphere sinks into the mantle at the subduction zones. The geological process which involves the recycling of the oceanic lithosphere into the Earth’s mantle mainly at convergent boundaries is referred to as subduction. With this, the subduction zone, therefore, is just where the cold oceanic lithosphere of the Earth sinks into the mantle to be recycled. Subduction zones are found at convergent plate boundaries; location of the converging of the oceanic lithosphere and the less dense lithosphere of two different plates.