Which of the Following Reactions, If Coupled to the Reduction $\alpha$

Which of the following reactions, if coupled to the reduction of $\alpha$ -ketoglutarate, would give the most exergonic overall reaction? $\alpha$ -ketoglutarate + CO₂ + 2H⁺ + 2e^- $\rarr$ isocitrate (E ^$\circ$ ' = - 0.38 V)

A) ubiquinol $\rarr$ ubiquinone + 2H⁺ + 2e^- (E ^$\circ$ ' = - 0.04 V)
B) FADH₂ $\rarr$ FAD + 2H⁺ + 2e^- (E ^$\circ$ ' = + 0.22 V)
C) NADH $\rarr$ NAD⁺ + H⁺ + 2e^- (E ^$\circ$ ' = + 0.32 V)
D) H₂ $\rarr$ 2H⁺ + 2e^- (E ^$\circ$ ' = + 0.42 V)
E) pyruvate + CoA $\rarr$ acetyl CoA + CO₂ + H⁺ + 2e^- (E ^$\circ$ ' = + 0.48 V)