Which type of fuel is NOT typically a source of carbon monoxide?

Electricity is not typically a source of carbon monoxide because it does not involve combustion. Carbon monoxide is produced when fuels that contain carbon, like fuel oil, gasoline, and natural gas, are burned and there is insufficient oxygen for complete combustion. During complete combustion, fuels transform into carbon dioxide and water, while incomplete combustion can lead to the production of carbon monoxide.

In contrast, electricity is a form of energy that does not produce emissions through combustion. Therefore, when considering sources of carbon monoxide, electricity stands out as the only option that does not contribute to the generation of this hazardous gas, which is why it is the correct answer.