Complex salt can be made by the combination of ${\left[{\mathrm{Co}}^{\mathrm{III}}{\left({\mathrm{NH}}_3\right)}_5\mathrm{Cl}\right]}^{\mathrm{x}}$ with

• A

  ${\mathrm{PO}}_4^{3-}$

• B

  ${\mathrm{Cl}}^{-}$

• C

  $2{\mathrm{Cl}}^{-}$

• D

  $2{\mathrm{K}}^{+}$