Fact 1: Hitting an object causes the particles in that object to vibrate.

Fact 2: Rock particles vibrate back and forth.

Given the two facts above, answer the question "Hitting a rock causes what?" with the following options: 
- heat energy
 - erosion
 - energy
 - friction
 - flooding
 - squeeze
 - contamination
 - vibration


 

        vibration 