Gold is leached by $4\mathrm{Au}+8\mathrm{NaCN}+\mathrm{O}{}_2+2\mathrm{H}{}_2\mathrm{O}\to 4\mathrm{Na}[\mathrm{Au}(\mathrm{CN}){}_2]+4\mathrm{NaOH}$ and recovered by $2\mathrm{Na}[\mathrm{Au}(\mathrm{CN}){}_2]+\mathrm{Zn}\to \mathrm{Na}{}_2[\mathrm{Zn}(\mathrm{CN}){}_4]+2\mathrm{Au}$. For $4.925\mathrm{g}$ of gold (Au = 197, Zn = 65, Na = 23, C = 12, N = 14), the masses of $\mathrm{NaCN}$ consumed in leaching and of zinc consumed in precipitation are respectively

1. A$1.23\mathrm{g}$ and $0.81\mathrm{g}$
2. B$2.45\mathrm{g}$ and $1.63\mathrm{g}$
3. C$4.90\mathrm{g}$ and $0.41\mathrm{g}$
4. D$2.45\mathrm{g}$ and $0.81\mathrm{g}$