Submerged steel pipes may be guarded against corrosion by fixing magnesium blocks onto them. Which equation shows the reaction that stops corrosion?
- A$\text{Fe} \rightarrow \text{Fe}^{2+} + 2e^{-}$
- B$\text{Fe}^{2+} \rightarrow \text{Fe}^{3+} + e^{-}$
- C$\text{Mg} \rightarrow \text{Mg}^{2+} + 2e^{-}$
- D$\text{Mg}^{2+} + 2e^{-} \rightarrow \text{Mg}$