Final answer:
The correct answer is a. Flavin adenine dinucleotide (FAD). It is a coenzyme similar to NAD⁺, involved in several redox reactions, and is derived from vitamin B₂.
Step-by-step explanation:
Flavin adenine dinucleotide (FAD) is a molecule similar to NAD⁺ in function, but it is a lower-energy coenzyme. The correct answer is a. Flavin adenine dinucleotide. FAD is a coenzyme involved in redox reactions within cells. It is composed of two nucleotides: adenosine diphosphate (ADP) and a second nucleotide derived from riboflavin (vitamin B₂). FAD can exist in two states: the oxidized form, FAD, and the reduced form, FADH₂.
It functions similarly to NAD⁺ (Nicotinamide adenine dinucleotide) in that it is involved in the transfer of electrons during cellular respiration. However, FAD is a more versatile coenzyme that can accept and donate electrons in a variety of oxidation-reduction reactions, significantly contributing to the energy extraction from sugars.