Answer
A
Work Step by Step
$Cr: [Ar]\ 3d^{5}\ 4s^1$ 6 unpaired
$Cr^{3+}: [Ar]\ 3d^{3}$ 3 unpaired
$Mn: [Ar]\ 3d^{5}\ 4s^2$ 5 unpaired
$Mn^{2+}: [Ar]\ 3d^{5}$ 5 unpaired
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