# Which one of the following is not a fossil fuel? (1) Coal (2) Oil (3) Natural Gas (4) Biogas

Fossil fuels are derived from decomposing plants and animals. Coal, oil and natural gas are examples of natural gas.  Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen, usually consisting of certain quantities of methane and other constituents. Therefore, biogas is not a fossil fuel.