You are presented with the question "What are most canyons caused by?" and the following answer choices: 
- erosion
 - Physical weathering
 - magic
 - Freezing temperature
 - Flowing water
 - ice wedging
 - Flowing gas
 - flooding

Now knowing that most canyons are formed by flowing rivers through erosion over long periods of time and rivers contain 0.001 percent of the earth's water, choose the best answer.


 

     Flowing water    