Answer: Flavin Adenine Dinucleotide (FAD)
Nicotinamide Adenine Dinucleotide (NAD)
Oxidation and reduction are coupled reactions in which electrons are transferred form one atom to another atom. Reduced compounds donate oxygen or accept hydrogen and oxidized compounds accepts oxygen or donates hydrogen.
So, when the electron carriers are in reduced condition, they accept hydrogens from different metabolic pathways, like glycolysis and TCA cycle, etc. In oxidized state they enter into ETC and donate protons for ATP synthesis. For example, 1 NADH gives 2.5 ATP and 1 FADH2 gives 1.5 ATP.
Step-by-step explanation: