Which process of reduction of mineral to the metal is suited for the extraction of copper from its ores with low copper content?

Impure silver ore $+ CN^{-} + H_2O \xrightarrow{O_2} [X]^{-} + OH^{-}$
$[X]^{-} + Zn \longrightarrow [Y]^{2-} + Ag \text{ (pure)}$
The coordination numbers of the metals in $[X]$ and $[Y]$ are respectively

$Ag_2S + NaCN \to (A)$,$(A) + Zn \to (B)$
$(B)$ is a metal. Hence,$(A)$ and $(B)$ are:

How is copper extracted from low grade copper ores?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In the Ellingham diagram,a sharp change in slope of the line is observed for $Mg \rightarrow MgO$ at $\sim 1120^{\circ} C$.
Reason $R$: There is a large change of entropy associated with the change of state.
In the light of the above statements,choose the correct answer from the options given below.

Which methods are used for the extraction of $Pb$ and $Sn$ from their respective ores?