Select the correct statement(s) about the cyanide process for silver and gold.

1. AGold is dissolved by aerated aqueous cyanide because $\mathrm{CN}{}^{-}$ stabilises gold(I) as $[\mathrm{Au}(\mathrm{CN}){}_2]{}^{-}$ and oxygen acts as the oxidant
2. BGold dissolves in cyanide solution through $\mathrm{Au}+2\mathrm{CN}{}^{-}\to [\mathrm{Au}(\mathrm{CN}){}_2]{}^{-}+\mathrm{e}{}^{-}$ even when no oxidant is present, so aeration is optional
3. CZinc dust added to $\mathrm{Na}[\mathrm{Ag}(\mathrm{CN}){}_2]$ solution gives silver and $\mathrm{Na}{}_2[\mathrm{Zn}(\mathrm{CN}){}_4]$
4. DThe complex ion $[\mathrm{Ag}(\mathrm{CN}){}_2]{}^{-}$ contains silver in the $+1$ state