Final answer:
The correct order of the electron transport chain complexes from the entry of electrons to their exit is Complex I, followed by Complex II, then Complex III, and finally Complex IV.
Step-by-step explanation:
The electron transport chain (ETC) complexes in mitochondria should be arranged in the order they participate in electron transport. First, Complex I (NADH-coenzyme Q oxidoreductase) or NADH dehydrogenase, is where electrons from NADH enter the ETC. The electrons are then transferred to ubiquinone (coenzyme Q). Although Complex II also transfers electrons to ubiquinone, it is not involved in pumping protons and receives electrons from FADH2 instead of NADH. After ubiquinone, the electrons move to Complex III (cytochrome b and c proteins or cytochrome oxidoreductase), which then transfers them to cytochrome c. Lastly, Complex IV (cytochrome c oxidase) receives electrons from cytochrome c and uses them to reduce oxygen into water, all while pumping additional protons across the membrane.
The correct order from the entry of electrons to their exit is: Complex I, Complex II, Complex III, Complex IV.