You are presented with the quiz "What is when solids are heated and ions move freely?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "melting is when solids are heated above their melting point" and "when melted or dissolved in water, the crystal lattice is destroyed and the ions move freely". 

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


 

 dissolving          