Which of the following statements is not correct?
$I$) Bond length order: $H_2^- = H_2^+ > H_2$
$II$) $O_2^+, NO, N_2^-$ have the same bond order of $2.5$
$III$) Bond order can assume any value including zero up to four
$IV$) $NO_3^-$ and $BO_3^{3-}$ have the same bond order for the $X-O$ bond (where $X$ is the central atom)

• A
  $I, II$ and $III$
• B
  $I$ and $IV$
• C
  $II$ and $IV$
• D
  $I$ and $II$