Which of the following best describes the electron transport chain?

• A. Electrons are pumped across a membrane by active transport.
• B. Acetyl CoA is fully oxidized to CO₂.
• C. Hydrogen atoms are added to CO₂ to make an energy-rich compound.
• D. Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle.
• E. Electrons are passed from one carrier to another, releasing a little energy at each step.