On the basis of the following $E^{\circ}$ values, the strongest oxidizing agent is :$[Fe(CN_6)]^{4-} \rightarrow [Fe(CN_6)]^{3-} +e^{-1} ; E^{\circ}= -0.35V \: \: \:$ $ Fe^{2+} \rightarrow Fe^{3+} + e^{-1} ; E^{\circ} = -0.77 V$

Question

$\begin {array} {1 1} (1)\;[Fe(CN_6)]^{3-} & \quad (2)\;[Fe(CN_6)]^{4-} \\ (3)\;Fe^{2+} & \quad (4)\;Fe^{3+} \end {array}$