Given below are two statements.
Statement $I:$ Frenkel defects are vacancy as well as interstitial defects.
Statement $II:$ Frenkel defect leads to colour in ionic solids due to presence of $F$-centres.
Choose the most appropriate answer for the statements from the options given below:

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