When $KI$ is passed through a solution containing $KCl, KF,$ and $KBr$,what happens?

• A
  $Cl_2$ and $Br_2$ are liberated.
• B
  $Cl_2$ is liberated.
• C
  $Cl_2, Br_2,$ and $F_2$ are liberated.
• D
  None of these.