Bleaching powder contains

• A
  $CaO$ and $Cl_{2}$ molecules
• B
  $Ca^{2+}$ and $OCl_{2}^{2-}$ ions
• C
  $Ca^{2+}, Cl^{-}, \text{and } OCl^{-}$ ions
• D
  $Ca^{2+}, O^{2-}$ ions and $Cl_{2}$ molecules