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 most coal is fossil peat. Given these facts, how is coal made among the following options:
- Being exposed to air
 - to move people
 - Converting waste.
 - heat is produced
 - It gets heated up
 - Being buried under ground
 - By hand
 - In a factory


 

      Being buried under ground   