The correct option is C Mn2++H2O2+2OH−⟶MnO2+2H2O
The unbalanced redox equation is as follows:
Mn2++H2O2⟶MnO2
All atoms other than H and O are balanced.
The oxidation number of Mn changes from 2 to 4. The change in the oxidation number is 2.
The oxidation number of O changes fro -1 to -2. The change in he oxidation number per O atom is 1. The total change in oxidation number for 2 O atoms is 2.
The increase in the oxidation number is balanced with decrease in the oxidation number.
The O atoms are balanced.
To balance H atoms, add two water molecules on RHS and two hydroxide ions to LHS.
Mn2++H2O2+2OH−⟶MnO2+2H2O
This is the balanced chemical equation.