What Happens First to the Carbon Atoms That Enter the Krebs

What happens first to the carbon atoms that enter the Krebs cycle as acetyl CoA?

A) They are reduced to form carbon dioxide.
B) They combine with a 4-carbon sugar to form a 6-carbon sugar citrate.
C) Two acetyl CoA molecules join together to form a 6-carbon sugar glucose.
D) They combine with pyruvate to form a 4-carbon sugar malate.
E) They are activated with a phosphate from ATP.