The correct option is C Mn3O4
Si+4, Na+, Mg2+ do not have an unpaired electron so they don't show magnetic property.
Mn3O4 exists as MnO.Mn2O3
Manganese is present in two oxidation states +2 and +3.
Outer electronic configuration of Mn3+ is 3d4
It has unpaired electrons hence it is paramagnectic in nature.