You are presented with the quiz "what can be done to salt water to cause water to evaporate while salt remains?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "heating salt water causes the water to evaporate while the salt remains" and "an increase in temperature is the result of the flow of heat into the system". 

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


 

        increasing the temperature   