In What Way Is the Reaction Shown a Key One

In what way is the reaction shown a key one in carbohydrate catabolism?

A) The reaction allows pyruvate to enter the citric acid cycle where it can be completely oxidized to CO₂.
B) The reaction represents the final step in aerobic respiration.
C) The reaction is the only NADH producing reaction in the citric acid cycle.
D) The reaction is the only decarboxylation reaction in the citric acid cycle.
E) The reaction represents the only energy-producing reaction of the citric acid cycle.