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.