When an excess of a very dilute aqueous solution of $KI$ is added to a very dilute aqueous solution of silver nitrate,the colloidal particles of silver iodide are associated with the Helmholtz double layer in the form of:

• A
  $AgI/Ag^{+}:I^{-}$
• B
  $AgI/K^{+}:NO_{3}^{-}$
• C
  $AgI/NO_{3}^{-}:Ag^{+}$
• D
  $AgI/I^{-}:K^{+}$