Which of the following will give a pair of enantiomers?

Options

1. A$\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]\left[\mathrm{Co}(\mathrm{CN})_6\right]$
2. B$\left[\mathrm{Co}(e n)_2 \mathrm{Cl}_2\right] \mathrm{Cl}$
3. C$\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]\left[\mathrm{PtCl}_6\right]$
4. D$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right] \mathrm{NO}_2$