You are presented with the question "What do glaciers do to rocks?" and the following answer choices: 
- form them
 - melt them
 - protect them
 - storing water
 - throw them
 - It expands
 - Water expanding
 - break them down

Now knowing that aglacier causes mechanical weathering and pysical weathering is the mechanical breakdown of rocks, choose the best answer.


 

        break them down 