You are presented with the question "What can you add to a solid to lower its freezing point?" and the following answer choices: 
- calcite
 - energy
 - heat
 - sodium
 - boiling
 - Solutions
 - salinity
 - Energy.

Now knowing that adding salt to a solid decreases the freezing point of that solid and another name for salt is sodium, choose the best answer.


 

    sodium     