From his experiments, S.L. Miller produced amino acids by mixing which of the following in a closed flask:

1. ${\mathrm{CH}}_3,$ ${\mathrm{H}}_2,$ ${\mathrm{NH}}_4$ $\mathrm{and}$ $\mathrm{water}$ $\mathrm{vapour}$ $\mathrm{at}$ $800°\mathrm{C}$

2. ${\mathrm{CH}}_4,$ ${\mathrm{H}}_2,$ ${\mathrm{NH}}_3$ $\mathrm{and}$ $\mathrm{water}$ $\mathrm{vapour}$ $\mathrm{at}$ $600°\mathrm{C}$

3. ${\mathrm{CH}}_3,$ ${\mathrm{H}}_2,$ ${\mathrm{NH}}_3$ $\mathrm{and}$ $\mathrm{water}$ $\mathrm{vapour}$ $\mathrm{at}$ $600°\mathrm{C}$

4. ${\mathrm{CH}}_4,$ ${\mathrm{H}}_2,$ ${\mathrm{NH}}_3$ $\mathrm{and}$ $\mathrm{water}$ $\mathrm{vapour}$ $\mathrm{at}$ $800°\mathrm{C}$