Aluminium is produced on a large scale by electrolysis of alumina,dissolved in fused cryolite and a little fluorspar. These two electrolytes,cryolite and fluorspar are respectively

• A
  $Na_3AlF_6$ and $CaF_2$
• B
  $AlF_3$ and $KF$
• C
  $Al_2Cl_6$ and $KCl$
• D
  $KCl \cdot MgCl_2 \cdot 6H_2O$ and $MgF_2$