Why are $Mn^{2+}$ compounds more stable than $Fe^{2+}$ towards oxidation to their $+3$ state?

(A) The electronic configuration of $Mn^{2+}$ is $[Ar] \, 3d^{5}$.
The electronic configuration of $Fe^{2+}$ is $[Ar] \, 3d^{6}$.
Half-filled and fully-filled orbitals are more stable due to exchange energy and symmetry. $Mn^{2+}$ has a stable half-filled $d^{5}$ configuration,making it resistant to oxidation to $Mn^{3+}$.
Conversely,$Fe^{2+}$ has a $3d^{6}$ configuration. By losing one electron,it achieves the stable half-filled $3d^{5}$ configuration. Therefore,$Fe^{2+}$ is easily oxidized to the $Fe^{3+}$ state.