The number of isomers possible for the octahedral complex ${\left[{\mathrm{CoCl}}_2\left(\mathrm{en}\right){\left({\mathrm{NH}}_3\right)}_2\right]}^{+}$ is,

The number of isomers that the octahedral complex is capable of having ${\left[{\mathrm{CoCl}}_2\left(\mathrm{en}\right){\left({\mathrm{NH}}_3\right)}_2\right]}^{+}$ is,

Two geometric isomers of the complex are produced.
There are d- and l-forms of this. As a result, the complex has a total of 4 potential isomers.

Hence, D is the right response. Four isomers