The type of isomerism shown by the complex $\left[\mathrm{C}\mathrm{o}\mathrm{C}{\mathrm{l}}_2\right(\mathrm{e}\mathrm{n}{)}_2]$ is

In $\left[\mathrm{C}\mathrm{o}\mathrm{C}{\mathrm{l}}_2\right(\mathrm{e}\mathrm{n}{)}_2]$ , Coordination number of Co is 6 and this compound has octahedral geometry.

As per given option, here the type of isomerism is geometrical isomerism.
It can not show ionization, coordination and linkage isomerisms as it does not fulfill required conditions for these isomerisms.