You are presented with the quiz "What does being buried under soil and mud change vegetation into?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "being burried under soil and mud changes vegetation into peat through extreme heat and pressure in a swamp over a long period of time" and "fossil fuels are concentrations of peat, coal, oil, and natural gas". 

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


 

    Fossil fuels       