Fact 1: Boiling means change from a liquid into a gas by adding heat energy.

Fact 2: Water, for example, is a liquid.

Given the two facts above, answer the question "What changes water into a gas by adding heat energy?" with the following options: 
- Energy.
 - precipitation
 - movement
 - a solute
 - coal
 - transpiration
 - boiling
 - ice


 

       boiling  