Oparin's hypothesis was tested by SL Miller by using which of the following chemicals in his experiment? 

SL Miller demonstrated the chemical evolution theory put forth by Heparin and Haldane. He recreated primitive atmosphere in his laboratory for the experiment. He used an  electric discharge in a closed flask containing ${\mathrm{CH}}_4$, ${\mathrm{H}}_2$, ${\mathrm{NH}}_3$ and water vapour at ${800}^{\mathrm{o}}\mathrm{C}$.