Final answer:
Coal is formed from plant remains that are buried before they decay and are then compacted into matter that is composed mainly of carbon and hydrocarbons.
Step-by-step explanation:
Coal is a complex solid material derived primarily from plants that died and were buried hundreds of millions of years ago and were subsequently subjected to high temperatures and pressures. It is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is formed from plant remains that are buried before they decay and are then compacted into matter that is composed mainly of carbon and hydrocarbons.