You are presented with the question "Adding what decreases the metling point of a liquid?" and the following answer choices: 
- gold
 - Heat energy
 - helium
 - fossil fuels
 - Sodium chloride
 - Calcium carbonate
 - dihydrogen monoxide
 - salinity

Now knowing that adding salt to a liquid decreases the melting point of that liquid and salt is sodium chloride or NaCl, choose the best answer.


 

     Sodium chloride    