During the extraction of gold,the following reactions take place: $4Au + 8CN^{-} + 2H_2O + O_2 \longrightarrow 4[Au(CN)_2]^{-} + 4OH^{-}$ and $2[Au(CN)_2]^{-} + Zn \longrightarrow [Zn(CN)_4]^{2-} + 2Au$. $X$ and $Y$ are respectively:

• A
  $[Au(CN)_2]^{-}$ and $[Zn(CN)_6]^{4-}$
• B
  $[Au(CN)_4]^{2-}$ and $[Zn(CN)_4]^{2-}$
• C
  $[Au(CN)_4]^{3-}$ and $[Zn(CN)_4]^{2-}$
• D
  $[Au(CN)_2]^{-}$ and $[Zn(CN)_4]^{2-}$