The highest manganese fluoride is MnF4, where the oxidation state of Mn is +4.
The highest manganese oxide is Mn2O7, where the oxidation state of Mn is +7.
The difference in oxidation states is ∣x∣=∣7−4∣=3.
The number of unpaired electrons in the given ions are:
Sc3+: [Ar]3d0⇒0 unpaired electrons
Zn2+: [Ar]3d10⇒0 unpaired electrons
V2+: [Ar]3d3⇒3 unpaired electrons
Fe2+: [Ar]3d6⇒4 unpaired electrons
Co2+: [Ar]3d7⇒3 unpaired electrons
Thus, V2+ (C) and Co2+ (E) have 3 unpaired electrons.
Answer: C and E Only