You are presented with the quiz "The origin of P-waves and S-waves can be traced back to what?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "faulting of rock in Earth 's crust causes earthquakes" and "earthquakes generate P waves and S waves which can travel throughout the earth". 

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


 

     Faulting of rocks in the crust      