Freezing means changing from a liquid into a solid by reducing heat energy, and liquid water holds a huge amount of heat energy and resists changes of state to solid or gas. Given these facts, what turns a liquid into a solid among the following options:
- The bending of a ray of light
 - decreasing liquid
 - reducing heat energy
 - Warm air moving into cold air
 - movement of tectonic plates
 - keeping current temperature
 - adding more heat
 - evaporation


 

   reducing heat energy      