Al₂O₃ can be converted into anhydrous AlCl₃ by heating

• A

  A mixture of Al₂O₃ and carbon in dry Cl₂ gas

• B

  ${\mathrm{Al}}_2{\mathrm{O}}_3\text{ with }{\mathrm{Cl}}_2\text{ gas }$

• C

  ${\mathrm{Al}}_2{\mathrm{O}}_3\text{ with }\mathrm{HCl}\text{ gas }$

• D

  ${\mathrm{Al}}_2{\mathrm{O}}_3\text{ with }\mathrm{NaCl}\text{ solid state }$