Given below are two statements:
Statement $I$: Corrosion is an electrochemical phenomenon in which pure metal acts as an anode and impure metal as a cathode.
Statement $II$: The rate of corrosion is more in alkaline medium than in acidic medium.
In the light of the above statements,choose the correct answer from the options given below:

• A
  Both Statement $I$ and Statement $II$ are false
• B
  Statement $I$ is false but Statement $II$ is true
• C
  Both Statement $I$ and Statement $II$ are true
• D
  Statement $I$ is true but Statement $II$ is false