Thermodynamics Terms

$CuFe{S}_2+O_2\stackrel{\text{�Partial�roasting�}}{\to }$
$C{u}_{2}S+FeO+S{O}_2+\underset{\text{�very�small�}}{\mathrm{FeS}}+\underset{\text{very�small}}{C{u}_{2}O}$
$C{u}_{2}S+O_2?C{u}_{2}O+S{O}_2$
$FeS+O_2?FeO+S{O}_2$
$FeO+Si{O}_2?FeSi{O}_3$
No formation of calcium silicate $\left(CaSi{O}_3\right)$ in extraction of $Cu$.

Step 1: Both reactions involve reduction from +4 to +2 oxidation state.
Step 2: Due to inert pair effect, stability of +2 state increases down the group.
Step 3: Tin ( ): +4 state is more stable than +2.
So reduction is non-spontaneous. Step 4: Lead ( ): +2 state is more stable due to inert pair effect.
So reduction is spontaneous. Hence, correct option is (2).