Right option is (b) Nitric oxide
Easy explanation: Car engines release only nitric oxides. Nitrogen and oxygen from the air combine at high temperatures in the engine to produce nitrogen (II) oxide by the reaction N2(g) + O2(g) → 2NO(g). Nitric oxides rise in the atmosphere and are oxidized to nitrogen dioxide, NO2 which dissolves in the precipitating water to form acid rain.