The standard reduction potentials at 298 K for the following half-cell reactions:
$Zn^{2+}_{\text{(aq)}} + 2e^- \rightarrow Zn_{\text{(s)}} \quad E^\circ = -0.762 \, \text{V}$
$Cr^{3+}_{\text{(aq)}} + 3e^- \rightarrow Cr_{\text{(s)}} \quad E^\circ = 0.740 \, \text{V}$
$2H^+_{\text{(aq)}} + 2e^- \rightarrow H_{2(\text{g})} \quad E^\circ = 0.0 \, \text{V}$
$F_{2(\text{g})} + 2e^- \rightarrow 2F^-_{\text{(aq)}} \quad E^\circ = 2.87 \, \text{V}$
Which of the following is the strongest reducing agent?