You are presented with the quiz "What enters the atmosphere when coal, oil, and natural gas is burned?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "burning fossil fuels increases the carbon in the atmosphere" and "carbon dioxide is produced by the burning of fossil fuels such as coal, oil and natural gas". 

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


 

       Carbon    