What Is Different About the Way That NADH and FADH₂

What is different about the way that NADH and FADH₂ donate electrons to the electron transport chain?

A) NADH is oxidized and FADH₂ is reduced.
B) NADH contributes its electrons to the first transmembrane complex in the electron transport chain and FADH₂ contributes its electrons after the first transmembrane complex.
C) More protons are transported into the intermembrane space of the mitochondria in response to one molecule of FADH₂ as compared to the number of protons transported in response to one molecule of NADH.
D) The electrons from NADH ultimately go on to reduce oxygen to generate water,whereas the electrons from FADH₂ are used to reduce pyruvate to lactate.