The correct answer is D) an oceanic plate subducts under a continental plate.
A deep ocean trench is formed when an oceanic plate subducts under a continental plate.
Natural phenomenon such as earthquakes deep down the ocean cans cause deep ocean trenches. The oceanic trench is a narrow and long depression at the bottom of the ocean. Scientists consider that it is 30,000 feet deep. This deep-sea trench can be found in places where tectonic plates subduct one under the other. For instance, we have the Mariana trench that is located in the North Pacific Ocean, close to the Mariana Islands.
