Fact 1: Breaking apart rocks can cause debris.

Fact 2: Sledge hammers can be used to break especially hard ledges of rock.

Given the two facts above, answer the question "What can be used to make debris?" with the following options: 
- erosion
 - rivers
 - a hammer
 - heat
 - wind
 - water pump
 - c-clamp
 - screwdriver


 

   a hammer      