Final answer:
NAD+ and FAD are both oxidizing agents as they accept electrons and get reduced to NADH and FADH2, thereby oxidizing other molecules and contributing to energy transfer for ATP creation.
Step-by-step explanation:
The pair of molecules that are both oxidizing agents is NAD+ and FAD. These molecules are crucial in cellular respiration, particularly in redox reactions where they accept electrons and get reduced to their respective forms, NADH and FADH2. This process allows for the transfer of energy that is used in the creation of ATP, an energy-rich molecule vital for cellular processes. NAD+ and FAD are thus oxidizing agents because they have the ability to oxidize other molecules by accepting electrons from them, becoming reduced in the process. In contrast, NADH and FADH2, their reduced forms, act as reducing agents and are used to store and transfer energy within the cell.
The pair of molecules that are both oxidizing agents are (a) NAD+ and (b) FAD. NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) are coenzymes involved in oxidation-reduction reactions, where they accept electrons and protons from organic molecules and get reduced to NADH and FADH2, respectively. These reduced coenzymes are energy-containing molecules used to transfer energy during the creation of ATP.