The $d - $electron configurations of ${\rm{C}}{{\rm{r}}^{2 + }},{\rm{\;M}}{{\rm{n}}^{2 + }},{\rm{\;F}}{{\rm{e}}^{2 + }}$ and ${\rm{C}}{{\rm{o}}^{2 + }}$ are ${d^4},{d^5},{d^6}\;and\;{d^7}$ respectively. Which one of the following will exhibit minimum paramagnetic behaviour? <br> (At. Nos.${\rm{Cr}} = 24,{\rm{\;Mn}} = 25,{\rm{\;Fe}} = 26,{\rm{\;Co}} = 27$)