In the cyclic reaction sequence called the krebs cycle, which chemical event does not take place?

In the cyclic reaction sequence called the krebs cycle, which chemical event does not take place? a.The acetyl group is joined with a four carbon molecule, oxaloacetate. b. Two carbons per cycle are made into CO2 molecules. c. Electrons generated are used to produce NADH. d. Pyruvate molecules are restored to the cycle. e. The resulting six carbon molecule is oxidized. I know it's not a. but that's as far as I have gotten.Any help would be greatly appreciated!