You are presented with the quiz "being burried under soil and mud changes how what forms?" 

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 "fens form non-acidic peat". 

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


 

   fens        