Fact 1: Adding salt to a liquid decreases the melting point of that liquid.

Fact 2: The addition of salt increases the density of water.

Given the two facts above, answer the question "What decreases the melting point of water?" with the following options: 
- 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


 

     increasing its density    