Which statement best describes what happens during the redox reaction between nadh and complex i of the electron transport chain? a. nadh is oxidized by fadh2 which is then immediately oxidized in complex complex ii. b. nadh is oxidized as a pair of electrons, which are transferred to the etc and 4 four h+ are pumped into the intermembrane space. c. ubiquinone receives two electrons from nadh and then moves throughout the hydrophobic interior of the etc membrane where it is oxidized by complex complex ii. d. two electrons from nadh are used to reduce oxygen gas (o2), which picks up two h+ form from the matrix to produce water.