You are presented with the question "What heats water for boiling?" and the following answer choices: 
- water
 - ice
 - magnets
 - Heat
 - ligt
 - fire
 - gas
 - salt

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


 

       gas  