Which one of the following has the largest number of isomers?

* $[\text{Co}(\text{en}{)}_2{\text{Cl}}_2{]}^{+}$ has geometrical isomers: $cis$ and $trans$. The $cis$ -isomer is non-superimposable on its mirror image, meaning it exists as a pair of optical isomers ($d$ and $l$). Thus, it has $3$ isomers total.$[\text{Ru}({\text{NH}}_3{)}_4{\text{Cl}}_2{]}^{+}$ has only $2$ geometrical isomers ($cis$ and $trans$).$[\text{Co}({\text{NH}}_3{)}_5\text{Cl}{]}^{2+}$ has no geometrical or optical isomers.$[\text{Co}(\text{en}{)}_2{\text{Cl}}_2{]}^{+}$ has the largest number among these.