Consider the following reduction processes :
$$Al^{3+} + 3e^{-} \rightarrow Al(s), E^{\circ} = -1.66V$$
$$Fe^{3+} + e^{-} \rightarrow Fe^{2+}, E^{\circ} = +0.77V$$
$$Co^{3+} + e^{-} \rightarrow Co^{2+}, E^{\circ} = +1.81V$$
$$Cr^{3+} + 3e^{-} \rightarrow Cr(s), E^{\circ} = -0.74V$$
The tendency to act as reducing agent decreases in the order :

Reduction potentials given:

$$Al^{3+}/Al: E° = -1.66$$ V
$$Fe^{3+}/Fe^{2+}: E° = +0.77$$ V
$$Co^{3+}/Co^{2+}: E° = +1.81$$ V
$$Cr^{3+}/Cr: E° = -0.74$$ V

A species acts as a reducing agent when it gets oxidized. The tendency to act as a reducing agent is related to the oxidation potential (negative of reduction potential). The more negative the reduction potential, the stronger the reducing agent.

Oxidation potentials: Al: +1.66, Cr: +0.74, $$Fe^{2+}$$: -0.77, $$Co^{2+}$$: -1.81.

Reducing agent strength: $$Al > Cr > Fe^{2+} > Co^{2+}$$.

The correct answer is Option A: $$Al > Cr > Fe^{2+} > Co^{2+}$$.