The correct option is B Hydrogen
Hydrogen fuel is a zero-emission fuel when burned with oxygen (if one considers water not as an emission) or used in a contained cell (allowing to react galvanically) also capable of 'reversing' the reaction if needed. It often uses electrochemical cells, or combustion in internal engines, to power vehicles and electric devices. It is also used in the propulsion of spacecraft and might potentially be mass-produced and commercialized for passenger vehicles and aircraft.