You are presented with the quiz "What causes volcanic eruptions?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "the movement of tectonic plates causes volcanic eruptions" and "the San Andreas is a "transform fault" that marks the boundary between two tectonic plates --  the North American and the Pacific". 

So, what's the best answer to the question?


 

     Two things that come together in San Andreas      