Answer- A. Pyruvate to oxaloacetateCarboxylation of pyruvate to oxuloacetate is an example of anaplerotic reactions."Anaplerotic reactions are chemical reactions that form intermediates of a metabolic pathway. Examples of such are foundin the citric acid cycle (TCA cycle).Examples of Anaplerotic ReactionsCarboxylation of pyruvate to oxaloacetateTransamination of aspaate to oxaloacetate by aspaate amino transferaseaHydration of glutamate to alpha-ketoglutarate by glutamate-dehydrogenaseBeta-oxidation of fatty acids to succinyl-CoAIn purine synthesis & purine nucleotide cycle: Adenylosuccinate to fumarate catalyzed by adenylosuccinate lyase.