You are presented with the quiz "Toasters convert what into an energy that can also light and cook?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "atoaster converts electrical energy into heat energy for toasting" and "early in human history, energy was first used by people for heating, lighting, and cooking". 

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


 

    electrical energy       