Final answer:
Supercomplexes of electron transport complexes are referred to as respirasomes, which optimize the efficiency of electron transfer and ATP synthesis in the inner mitochondrial membrane.
Step-by-step explanation:
Supercomplexes of electron transport complexes are known as D) respirasomes. These structures are formed within the inner mitochondrial membrane and consist of several electron transport chain complexes that work together to facilitate the transfer of electrons from donors like NADH and FADH2 to oxygen, the final electron acceptor. Respirasomes enhance the efficiency of electron transport and ATP synthesis by bringing these complexes into close proximity to each other, reducing the diffusion distance for electron carriers such as ubiquinone (coenzyme Q) and cytochrome c.
Complex I or NADH dehydrogenase is the first complex and it transfers electrons to ubiquinone, which then delivers the electrons to Complex III, or cytochrome oxidoreductase. Complex III in turn transfers the electrons to cytochrome c, which delivers them to Complex IV, where they ultimately reduce oxygen to water. Complex II or succinate dehydrogenase is another entry point for electrons into the electron transport chain but does not form part of the respirasome.