Given below are two statements:
Statement $I$: The $N-N$ single bond is weaker and longer than the $P-P$ single bond.
Statement $II$: Compounds of group $15$ elements in $+3$ oxidation state readily undergo disproportionation reactions.
In the light of the above statements,choose the correct answer from the options given below:

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