Why was the first organism on Earth able to survive?

How does the fermentation of pyruvic acid in cells contribute to the formation of atp? a. it completes the oxidation of glucose to co2, creating atp. b. it generates lactic acid, which cycles back through the krebs cycle, producing 2 atp molecules. c. it converts fadh2 to phosphate, which bonds with adp. d. it produces 2 nad+ molecules, which cycle back to fuel the glycolysis reaction, allowing 2 atp molecules to be produced.