Given below are two statements:
Statement $I$: $Adenosine \ deaminase$ is crucial for the immune system to function.
Statement $II$: $Adenosine \ deaminase$ deficiency can be cured only by bone marrow transplantation.
In the light of the above statements, choose the correct answer from the options given below.

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