For the formation of which compound in the Ellingham diagram does $\Delta G^{\circ}$ become more and more negative with an increase in temperature?

Statement $(A)$ $Mg$ can reduce $Al_2O_3$ above $1350^{\circ} C$.
Statement $(B)$ $Al$ can reduce $MgO$ below $1350^{\circ} C$.
The correct answer is

The reactions which occur in a blast furnace at $500-800 \ K$ during the extraction of iron from haematite are:
$(i)$ $3 Fe_2O_3 + CO \rightarrow 2 Fe_3O_4 + CO_2$
$(ii)$ $Fe_2O_3 + 3 C \rightarrow 2 Fe + 3 CO$
$(iii)$ $Fe_3O_4 + 4 CO \rightarrow 3 Fe + 4 CO_2$
$(iv)$ $Fe_2O_3 + CO \rightarrow 2 FeO + CO_2$

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:

Heating a mixture of $Cu_2O$ and $Cu_2S$ will give:

Why is zinc not extracted from zinc oxide through reduction using $CO$?