Which one of the following fuels causes minimum environmental pollution ?

(c) Except hydrogen, all the rest three options diesel, coal and kerosene are either naturally occurring fossil fuels or derived from them. Thus as we know naturally occuring fossil fuels and their products have high percentage of carbon which on combustion lead to discharge of oxides by carbon (CO₂ & CO) in air. This results in to heavy environmental pollution like CO₂ results in to green house effect causes global warming While CO is poisonous in nature, it combines with haemoglobin of blood to form carboxyhaemoglobin. Hydrogen fuel as such causes no pollution because on combustion with oxygen it forms water that's why it is also called future fuel.