I think it’s B. Using a video from amoeba sisters.
It is due to the electron transport chain that is located in the mitochondria
Explanation:
the Krebs cycle occurs on the mitochondrial matrix and generates a pool of chemical energy from the oxidation of pyruvate, the end product of glycolysis. pyruvate is transported into the mitochondria and loses carbon dioxide to form acetyl-CoA, a 2-carbon molecule
Within a protein, multiple amino acids are linked together by peptide bonds, causing them to form a long chain. its easy to remember by thinking of the amino acids hooking up like a trains cars.