Oxidation number of $Cl$ in $CaOCl_2$ (bleaching powder) is

• A
  Zero,since it contains $Cl_2$
• B
  $-1$,since it contains $Cl^{-}$
• C
  $+1$,since it contains $ClO^{-}$
• D
  $+1$ and $-1$ since it contains $ClO^{-}$ and $Cl^{-}$