You are presented with the question "Shifting in the Earth's crust are caused by what?" and the following answer choices: 
- Greenhouse gases
 - rock beds
 - friction
 - avalanches
 - fault in rocks
 - no movement in the crust
 - Movement
 - Time and energy

Now knowing that faulting of rock in Earth 's crust causes earthquakes and earthquakes and volcanoes are violent proof of Earth's shifting crust, choose the best answer.


 

     fault in rocks    