Given the standard electrode potentials: $Fe^{2+}_{(aq)} + 2e^{-} \rightarrow Fe_{(s)}$ $(E^o = -0.44 \ V)$ and $Fe^{3+}_{(aq)} + e^{-} \rightarrow Fe^{2+}_{(aq)}$ $(E^o = 0.77 \ V)$. If $Fe^{2+}$,$Fe^{3+}$,and a piece of $Fe$ are kept together,what happens?

• A
  $Fe^{3+}$ concentration increases.
• B
  $Fe^{3+}$ concentration decreases.
• C
  The ratio $\frac{[Fe^{2+}]}{[Fe^{3+}]}$ remains constant.
• D
  $Fe^{2+}$ concentration decreases.