You are presented with the quiz "The sun causes water to change partially to gas by doing what?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "the sun causes water to evaporate more quickly by adding heat" and "evaporation is when the sun heats the water and changes some of it to gas". 

So, what's the best answer to the question?


 

 adding heat          