Which among the following statement(s) is(are) true for the extraction of aluminium from bauxite?

2NaAl(OH)4(aq.)+CO2⟶Na2CO3+H2O+2Al(OH)3(↓)                                                                                       (or)                                                                           Al2O3⋅2H2O(ppt)(B) Function of Na3AlF6 is to lower the melting point of electrolyte.(C) During electrolysis of Al2O3, the reactions at anode are :2Al3+(ℓ)+3O2−(ℓ)⟶ At anode O2( gas )+2e−C (graphite) +O2⟶CO(↑)+CO2(↑)(D) The steel vessel with a lining of carbon acts as cathode