- A NAD⁺
- B ATP
- C oxygen
- D glucose
Correct answer: A. NAD⁺
Explanation: Fermentation reoxidises NADH to NAD⁺, allowing glycolysis to keep running without oxygen.
Concept context
Glycolysis, the Krebs cycle, the electron transport chain, fermentation, and the respiratory quotient. The cellular energy-release counterpart to photosynthesis.