Disproportionation of $1 \ mol$ of $MnO_4^{2-}$ in neutral aqueous solution results in which of the following?

• A
  $\frac{2}{3} \ mol$ of $MnO_4^-$ and $\frac{1}{3} \ mol$ of $MnO_2$
• B
  $\frac{1}{3} \ mol$ of $MnO_4^-$ and $\frac{2}{3} \ mol$ of $MnO_2$
• C
  $\frac{2}{3} \ mol$ of $Mn_2O_7$ and $\frac{1}{3} \ mol$ of $MnO_2$
• D
  $\frac{2}{3} \ mol$ of $Mn_2O_7$ and $\frac{1}{3} \ mol$ of $Mn_2O_3$