You are presented with the quiz "what being buried under mud changes peat into coal?" 

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 peat into coal through extreme heat and pressure in a swamp over a long period of time" and "peat moss is the organic matter that mixes with soil to form peat". 

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


 

      organic matter     