You are presented with the question "What changes water into a gas by adding heat energy?" and the following answer choices: 
- Energy.
 - precipitation
 - movement
 - a solute
 - coal
 - transpiration
 - boiling
 - ice

Now knowing that boiling means change from a liquid into a gas by adding heat energy and water, for example, is a liquid, choose the best answer.


 

       boiling  