The correct option is D A pathway that produces substrates that can be used to build biomolecules and/or produce ATP.
Amphibolic pathways are pathways that are both catabolic and anabolic in nature. That is, the substrates produced in these pathways can be sent into the oxidative phosphorylation cycle to produce ATP, or they can be recycled into any of the anabolic pathways for production of important biomolecules. Glycolytic pathway, Kreb's cycle etc are examples for amphibolic pathways. ETC or electron transport chain is only catabolic in nature, as it plays a role only in the production of ATP and do not produce substrates for anabolic processes.