In glycolysis, glucose is split into two pyruvate molecules and 2 ATP molecules are generate per molecule of glucose as well as 2 molecules of NADH Krebs Cycle uses the pyruvate molecules from glycolysis to generate 2 ATP as well as several molecules of FADH2 and NADH for the electron transport chain So neither of those 2 is correct. Electron transport chain uses the NADH and FADH2 molecules formed during glycolysis and krebs cycle