You are presented with the question "Wave action causes?" and the following answer choices: 
- fissures of hot, acidic water
 - contact between rocks
 - Animal survival
 - Electrical energy
 - scattered light
 - flow of electrons
 - electromagnetic energy
 - energy of moving objects

Now knowing that contact between rocks over long periods of time causes rocks to smooth and because of the big wave action, the rocks are very smooth, choose the best answer.


 

  contact between rocks       