Answer: Carbon monoxide
Explanation: Carbon monoxide is an odorless, colorless gas that is formed by the incomplete combustion of fuels. It can be deadly to humans if inhaled in large amounts, as it can prevent the body from receiving enough oxygen. Nitrogen and ethanol are both gases, but they do not have the same properties as carbon monoxide and are not dangerous in the same way. Nitrogen is a relatively inert gas that makes up most of the Earth's atmosphere, and ethanol is a type of alcohol that is commonly found in alcoholic beverages.