Which one of the following complexes shows optical isomerism?

Options

A $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3 \mathrm{Cl}_3\right]$
Bcis- $\left[\mathrm{Co}(e n)_2 \mathrm{Cl}_2\right] \mathrm{Cl}$
Ctrans- $\left[\mathrm{Co}(e n)_2 \mathrm{Cl}_2\right] \mathrm{Cl}$
D $\begin{aligned} & {\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right] \mathrm{Cl}} \\ & \text{ (en= ethylenediamine) }\end{aligned}$

B. cis- $\left[\mathrm{Co}(e n)_2 \mathrm{Cl}_2\right] \mathrm{Cl}$

\left[\mathrm{Co}

\left(\mathrm{NH}_3\right)_3 \mathrm{Cl}_3\right]

has two geometrical isomers but both are optically inactive due to plane of symmetry. cis-

\left[\mathrm{Co}(e n)_2 \mathrm{Cl}_2\right] \mathrm{Cl}

is optically active. Which one of the following complexes shows optical isomerism?

Non -superimposable mirror images trans-

\left[\mathrm{Co}(e n)_2 \mathrm{Cl}_2\right] \mathrm{Cl}

is optically inactive due to plane of symmetry.

\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right] \mathrm{Cl}

has two geometrical isomers but both are optically inactive due to plane of symmetry.