Final answer:
NADH and FADH2 provide high-energy electrons to the electron transport chain located in the mitochondria, where ATP is produced as a result of this process.
Step-by-step explanation:
NADH and FADH2 pass high-energy electrons to the electron transport chain. The correct answer to where this process occurs is B) Coenzymes, Mitochondria. The electron transport chain is part of cellular respiration and takes place in the inner membrane of the mitochondrion. High-energy electrons from NADH and FADH2 are passed to various electron carriers within the chain. As electrons move through the electron transport chain, a gradient is formed by the pumping of protons across the membrane. This gradient is then utilized to produce ATP, the energy currency of the cell.