Which of the following conversion is correct for indicated process?

The following reaction involves self-reduction,

${\mathrm{PbSO}}_4+\mathrm{PbS}⟶\mathrm{Pb}+2{\mathrm{SO}}_2$

Another name for this procedure is the "air reduction process" or "auto reduction method."

$\mathrm{Hg},\mathrm{Pb},\mathrm{Cu}$ and other less electropositive metals' sulphide ores are heated in the air so that some of the ore is converted into oxide or sulphate, which then interacts with the remaining sulphide ore to produce the metal and sulphur dioxide.

This procedure doesn't employ any external reducing agents.

Hence, option B is correct.