\textbf{233 –} Considering the information below, which metal M can have the standard reduction potential?
$$\mathrm{M(s) + Hg^{2+}(aq) \rightarrow Hg(s) + M^{2+}(aq)}$$
$$\mathrm{M^{2+}(aq) + Sn(s) \rightarrow \text{ does not occur}}$$
$$\mathrm{M(s) + Mg^{2+}(aq) \rightarrow \text{ does not occur}}$$
$$\mathrm{M^{2+}(aq) + Mn(s) \rightarrow M(s) + Mn^{2+}(aq)}$$
\hfill
$\mathrm{E^\circ(Hg^{2+}(aq)/Hg(s)) = +0/85\ V}$
$\mathrm{E^\circ(Sn^{2+}(aq)/Sn(s)) = -0/14\ V}$
$\mathrm{E^\circ(Mg^{2+}(aq)/Mg(s)) = -2/38\ V}$
$\mathrm{E^\circ(Mn^{2+}(aq)/Mn(s)) = -1/18\ V}$
(1) $+0/11$ \quad (2) $-0/11$ \quad (3) $-0/40$ \quad (4) $+1/2$