A complex salt is a salt that contains a complex molecule that serves as both the salt's cationic and anionic components. Basic Lead Carbonate, sometimes referred to as White Lead, is a complex salt that likewise comprises the same core metal, lead, as well as carbonate and hydroxyl ions (Pb).

A complicated salt that includes both carbonate and hydroxide ions is basic lead carbonate. It is found naturally as the mineral hydrocerussite, sometimes known as a cerussite hydrate. Due to its opacity and capacity to combine with dryable oils to make a satiny smooth combination, it was once a component of lead paint.

Basic lead carbonate is a complex molecule. It contains two entities as anion and cation. The chemical formula of lead carbonate in basic solution is; $2{\mathrm{PbCO}}_3.\mathrm{Pb}{\left(\mathrm{OH}\right)}_2$

Thus, value of 'X' is two.

Hence, option B is correct.