Given below are two statements.
Statement $I$ - Graphical recording of electrical variations detected at the surface of body during their propagation through the wall of heart is electrocardiograph.
Statement $II$ - The instrument used for the graphical recording of electrical variations detected at the surface of body during their propagation through wall of heart is electrocardiogram.
In the light of above statements,select the correct option given below:

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