Which of the following correctly describes the electron transport chain? Here, the harnessing of energy from high-energy electrons from the Krebs Cycle is considered. That's true because, remember, the production of NADH and FADH2 represent high-energy molecules. They get shuttled over to the electron transport chain, and we harness their energy from their electrons to eventually generate ATP. So this is true.
The breakdown of NADH and FADH2 to carbon dioxide is incorrect. They just pass along their electrons, become oxidized, and return back to their NAD+ and FAD structures. So, they're not being changed into carbon dioxide.
Oxidation of NADH and FADH2 coenzymes is correct. They give up their electrons, with NADH giving its electrons to Complex 1 to become NAD+ again, and FADH2 hands over its electrons to Complex 2 to become FAD again. Since they are losing electrons, they are being oxidized.
Redox reactions are facilitated by enzyme complexes and electron carriers located in the inner membrane of the cell. So, remember, this happens in different places: it's within the inner membrane, yes, with the embedded enzyme complexes. However, NADH and FADH2 are part of the mitochondrial matrix. This description does not take that location into account fully. So this is not completely true.
Here, the answer would be options A and option C.