Answer: The correct answer is Link reaction ( formation of acetyle CoA from pyruvate).
In this reaction acetyl-Coenzyme A ( which is a two-carbon molecule) is produced from pyruvate ( three-carbon molecule, produced from glycolysis). Acetyl CoA is required for the citric acid cycle.
In the link reaction, two molecules of hydrogen and CO₂ are released from two molecules of pyruvate, forming two acetyl CoA.
This reaction occurs in the mitochondrial matrix