The Reaction of the Citric Acid Cycle That Is Most $\alpha$

The reaction of the citric acid cycle that is most similar to the pyruvate dehydrogenase complex-catalyzed conversion of pyruvate to acetyl-CoA is the conversion of:

A) citrate to isocitrate.
B) fumarate to malate.
C) malate to oxaloacetate.
D) succinyl-CoA to succinate.
E) $\alpha$ -ketoglutarate to succinyl-CoA.