A) Acetyl CoA is produced from catabolism of carbohydrates, lipids, and proteins, and it directly provides electrons to the electron transport chain. B) Acetyl CoA is produced from catabolism of carbohydrates, lipids, and proteins, and it is a substrate for the Krebs cycle and for lipid synthesis. C) Acetyl CoA provides electrons to the electron transport chain and is a substrate for fatty acid synthesis. D) Acetyl CoA is a breakdown product of lipid catabolism and is produced in the cytosol by glycolysis. E) Acetyl CoA is a breakdown product of lipid catabolism and a substrate for carbohydrate synthesis.