Fact 1: If soil is permeable then water easily flows through that soil.

Fact 2: The increase in permeability is caused by the formation and expansion of ice in the soil.

Given the two facts above, answer the question "Water can flow easily through soil where what has formed and expanded?" with the following options: 
- bogs
 - rock
 - Sand
 - ice
 - moss
 - dam
 - peat
 - stem


 

    ice     