Consider the cell potentials ${\mathrm{E}}_{{\mathrm{Mg}}^{2+}\left|\mathrm{Mg}\right.}^0=-2.37\mathrm{V}$ and ${\mathrm{E}}_{{\mathrm{Fe}}^{3+}\left|\mathrm{Fe}\right.}^0=-0.04\mathrm{V}$. The best reducing agent would be

A metal with highest sop is best reducing agent.

Metal electrode with lowest standard reduction potential right hand species is best reducing agent as it under goes readily oxidation.

Metal electrode with highest standard reduction potential left hand species is best oxidizing agent as it under goes readily reduction.