OK so very difficult but I will try,
I can say for certain that it's really probably not A. or D.
As for B. or C., I'd say C.
Answer:
series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate
Explanation:
The citric acid cycle, also known as the Krebs cycle or the tricarboxylic acid cycle, is at the center of cellular metabolism, playing a starring role in both the process of energy production and biosynthesis. It finishes the sugar-breaking job started in glycolysis and fuels the production of ATP in the process.
