You are presented with the question "What decreases the melting point of water?" and the following answer choices: 
- The bending of a ray of light
 - heating liquids
 - cloudy and rainy weather
 - Movement of an air mass
 - increasing its density
 - global warming
 - tectonic plates coliding
 - movement of tectonic plates

Now knowing that adding salt to a liquid decreases the melting point of that liquid and the addition of salt increases the density of water, choose the best answer.


 

     increasing its density    