In option A: ${\left[\mathrm{C}\mathrm{o}\mathrm{C}{\mathrm{l}}_4\right]}^{2-},\mathrm{C}{\mathrm{o}}^{2+}\left(3{\mathrm{d}}^7\right)$ with W.F.L.,



and $\left[\mathrm{F}\mathrm{e}\right({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},\mathrm{F}{\mathrm{e}}^{2+}\left(3{\mathrm{d}}^6\right)$ with W.F.L.,



In option B: $\left[\mathrm{C}\mathrm{r}\right({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},\mathrm{C}{\mathrm{r}}^{2+}\left(3{\mathrm{d}}^4\right)$ with W.F.L.,



and $[\mathrm{C}\mathrm{o}\mathrm{C}{\mathrm{l}}_4{]}^{2-},\mathrm{C}{\mathrm{o}}^{2+}(3{\mathrm{d}}^7)$ with W.F.L.,



In option C: $\left[\mathrm{C}\mathrm{r}\right({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},\mathrm{C}{\mathrm{r}}^{2+}\left(3{\mathrm{d}}^4\right)$ with W.F.L.,



and $\left[\mathrm{F}\mathrm{e}\right({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},\mathrm{F}{\mathrm{e}}^{2+}\left(3{\mathrm{d}}^6\right)$ with W.F.L.,



Here both complexes have same unpaired electrons i.e. = 4

In option D: $\left[\mathrm{M}\mathrm{n}\right({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},\mathrm{M}{\mathrm{n}}^{2+}\left(3{\mathrm{d}}^5\right)$ with W.F.L.,



and $\left[\mathrm{C}\mathrm{r}\right({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},\mathrm{C}{\mathrm{r}}^{2+}\left(3{\mathrm{d}}^4\right)$ with W.F.L.,