Answer;
-Carbon
Step-by-step explanation;
-Fossils are formed in a number of different ways, but most are formed when a plant or animal dies in a watery environment and is buried in mud and silt. They formed from organic remains of plants and animals that were converted into coal, oil or natural gas by exposure to heat and the pressure of the Earth’s crust over millions of years.
-Fossil fuels are hydrocarbons comprised primarily of the following elements: carbon and hydrogen and some sulfur, nitrogen, oxygen, and mineral matter. For example, Natural Gas and coal are made up of carbon, hydrogen, nitrogen, sulfur and oxygen. Oil, or petroleum, also consists of carbon, hydrogen, sulfur, oxygen and nitrogen, but it is in liquid form.