In the following process:

$\begin{array}{r}{\mathrm{Ag}}_2\mathrm{S}+\mathrm{NaCN}+{\mathrm{O}}_2\rightleftharpoons \text{ Complex }\mathrm{X}\\ +{\mathrm{Na}}_2\mathrm{S}\end{array}$

Which option is incorrect for above process? 

The following reaction is obtained when the silver sulfide reacts with the sodium cyanide and oxygen,

${\mathrm{Ag}}_2\mathrm{S}+{\mathrm{O}}_2+\mathrm{NaCN}\to \mathrm{NaAg}{\left(\mathrm{CN}\right)}_2+{\mathrm{Na}}_2\mathrm{SO}4$

Due to the Presence of oxygen in the above process ${\mathrm{Na}}_2\mathrm{S}$ is oxidized into  ${\mathrm{Na}}_2{\mathrm{SO}}_4$ and it is a type of hydrometallurgy process.

Hence the correct option is B