In the commercial electrochemical process for aluminium extraction the electrolyte used is 

The electrolyte used in the commercial electrochemical technique for extracting aluminum is a molten  combination  of ${\mathrm{Al}}_2{\mathrm{O}}_3,{\mathrm{Na}}_3{\mathrm{AlF}}_6$ and ${\mathrm{CaF}}_2$ 

The electrolyte used in the industrial electrochemical method of extracting aluminum is. a molten  combination  of ${\mathrm{Na}}_3{\mathrm{AIF}}_6$ and ${\mathrm{Al}}_2{\mathrm{O}}_3$ (cryolite). and  ${\mathrm{CaF}}_2$

Hence Correct option is C