In which of the following cells will be the emf be independent of the activity of the chloride ions ?

Question

$\begin{array}{1 1} 2n |2ncl_2(aq) ||p+(cl_2)| \\ 2n |2ncl_2(aq) ||p-(cl_2)|\\Ag.Agcl_{(r)}|KCl_{(aq)}| P+(Cl_2) \\ 2n |4ncl_2(aq) ||p+(cl_2)| \end{array}$