The correct statement regarding $ClO_n^-$ molecular ion is

• A
  On decreasing value of $n$,$Cl-O$ bond order increases
• B
  On increasing value of $n$,$Cl-O$ bond length increases
• C
  On increasing value of $n$,oxidation number of central atom increases
• D
  On increasing value of $n$,hybrid orbitals on central atom increase