Where are earthquakes and volcanoes most likely to occur

C. That is the ring of fire

Almost earthquakes and volcanoes form on fault lines and tectonic plates. This happens due to the plates shifting and moving. When shifting, they can cause a sudden large jolt around the area which is also called an earthquake. That also goes for volcanoes too though because when two plates "smash" into one another, it can create a mountain and/or a volcano. I hope this helped clear things up for you! :D