In the commercial electro chemical process for aluminium extraction the electrolyte used is

Question

$\begin{array}{1 1} Al(OH)_3 \text{in NaOH solution } \\ \text{an aqueous solution of} Al_2(SO_4) _3\\ \text{a molten mixture of} Al_2O_3\;and\;Na_3AlF_6 \\ \text{a molten mixture of} Al_2O_3 \;and\; CAl(OH)_3 \end{array}$