Answer:
The correct answer would be "NADH delivers its electrons to complex I and FADH₂ deliver its electrons to complex II" in cellular respiration.
There are mainly four complexes associated with electron transport chain of cellular respiration.
Complex I or NADH: ubiquinone oxidoreductase is the complex at which NADH is oxidized to form NAD⁺. The free electrons are transported with the help of ubiquinone.
Complex II or succinate dehydrogenase is the complex associated with oxidation of FADH₂ to FAD⁺. It also transports the free electrons with the help of the ubiquinone pool.
Complex III or cytochrome bc1 complex transport free electrons from ubiquinone to the cytochrome C which is a water-soluble electron carrier.
Complex IV or cytochrome c oxidase transport the free electrons to oxygen to form water.