What is the abbreviated electron configuration of the cobalt(II) ion, ${\text{C}}{{\text{o}}^{2 + }}$?

A.     ${\text{[Ar]3}}{{\text{d}}^{\text{7}}}$

B.     ${\text{[Ar]4}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{d}}^{\text{5}}}$

C.     ${\text{[Ar]4}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{d}}^{\text{7}}}$

D.     ${\text{[Ar]4}}{{\text{s}}^{\text{1}}}{\text{3}}{{\text{d}}^{\text{6}}}$

A