The odd one out in this list is Biogas. This is because Natural Gas, Gasoline, and Coal are all fossil fuels, whereas Biogas is a renewable energy source. Biogas is produced from organic waste materials such as agricultural waste, sewage, and food waste through a process called anaerobic digestion. Unlike the other three options, Biogas is considered a more sustainable and environmentally friendly fuel option as it reduces greenhouse gas emissions and utilizes waste materials.