In the context of the Hall-Heroult process for the extraction of $Al$,which of the following statements is false?

• A
  $Al^{3+}$ is reduced at the cathode to form $Al$
• B
  $Na_3AlF_6$ serves as the electrolyte
• C
  $CO$ and $CO_2$ are produced in this process
• D
  $Al_2O_3$ is mixed with $CaF_2$ which lowers the melting point of the mixture and brings conductivity