You are presented with the quiz "What can fatty acids be combined with, in addition to carbon and oxygen?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "lipids may consist of fatty acids alone, or they may contain other molecules as well" and "lipids Lipids are also composed of carbon, oxygen and hydrogen". 

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


 

       Hydrogen    