In electrolytic refining of lead, e1ectrolyte consists of

In the electrolytic refining of lead, e1ectrolyte consists of  ${\mathrm{H}}_2{\mathrm{SiF}}_6\text{ and }{\mathrm{PbSiF}}_6$ Hexafluoro silicic acid $\left({\mathrm{H}}_2{\mathrm{SiF}}_6\right)$ and lead fluorosilicate $\left({\mathrm{PbSiF}}_6\right)$ are combined to provide the electrolyte for this process, which is carried out at a temperature of 45 °C (113 °F). Anodes are cast from the impure lead to be refined, and cathodes are thin sheets of pure lead.

Hence, option D is correct.