Given $E^{\circ }(\mathrm{H}{}^{+}/\mathrm{H}{}_2)=0.00$, $E^{\circ }(\mathrm{O}{}_2,\mathrm{H}{}^{+}/\mathrm{H}{}_2\mathrm{O})=1.23$, $E^{\circ }(\mathrm{Na}{}^{+}/\mathrm{Na})=-2.71$, $E^{\circ }(\mathrm{Cu}{}^{2+}/\mathrm{Cu})=0.34$, $E^{\circ }(\mathrm{Ag}{}^{+}/\mathrm{Ag})=0.80$, $E^{\circ }(\mathrm{F}{}_2/\mathrm{F}{}^{-})=2.87\mathrm{V}$. Which pair of species is thermodynamically unstable in $1\mathrm{M}$ aqueous acid under standard conditions, one by reducing $\mathrm{H}{}^{+}$ and the other by oxidising water?

1. ANa and Ag
2. BCu and $\mathrm{F}{}_2$
3. CNa and $\mathrm{F}{}_2$
4. DAg and Cu