Why is the value for `(Mn^(3+))/(Mn^(2+))` couple much more positive than that for `(Cr^(3+))/(Cr^(2+))` or `(Fe^(3+))/(Fe^(2+))`? Explain
A. much larger third ionisation energy of Mn
B. Much smaller third ionisation energy of Mn
C. `Mn^(3+)`is most stable
D. very low enthalpy of atomisation value of Mn among the `3d` series elements
