Which of the following is the true statement that describes the flow of energy in the citric acid cycle?

1. Energy is required in the energy-investment phase of steps 1-4 and released during the energy payoff phase of steps 1-8.
2 .Glucose is fully oxidized and the energy is released all together as ATP.
3. Energy is released in step #6 when FAD is reduced to FADH2.
4. Energy is transformed by the oxidation of acetyl CoA and reduction of NAD+ and FAD.
5. Energy in the bonds of CO2 is released in step #3 and in step #4.