Given below are two statements:
Statement $I$: During electrolytic refining,the pure metal is made to act as anode and its impure metallic form is used as cathode.
Statement $II$: During the Hall-Heroult electrolysis process,purified $Al_2O_3$ is mixed with $Na_3AlF_6$ to lower the melting point of the mixture.
In the light of the above statements,choose the most appropriate answer from the options given below:

• A
  Statement $I$ is incorrect but Statement $II$ is correct
• B
  Both Statement $I$ and Statement $II$ are incorrect
• C
  Statement $I$ is correct but Statement $II$ is incorrect
• D
  Both Statement $I$ and Statement $II$ are correct