Regardless of the electron or hydrogen acceptor used, one of the products of fermentation is always:

• A. CO\(_2\)
• B. NAD+
• C. ATP
• D. O\(_2\)

Answer: (B)

Verified step by step guidance

1. Understand the process of fermentation: Fermentation is an anaerobic process (does not require oxygen) that allows cells to regenerate NAD+ from NADH, enabling glycolysis to continue producing ATP.
2. Identify the key components of fermentation: During fermentation, pyruvate (produced in glycolysis) is converted into various end products depending on the organism and conditions. Common products include lactic acid, ethanol, and CO\(_2\), but the regeneration of NAD+ is a universal feature.
3. Recognize the role of NAD+: NAD+ is a crucial electron carrier that must be regenerated during fermentation to sustain glycolysis. Without NAD+, glycolysis would halt, and the cell would not produce ATP.
4. Eliminate incorrect options: CO\(_2\) is a product of some types of fermentation (e.g., alcoholic fermentation), but not all. ATP is produced during glycolysis, not directly during fermentation. O\(_2\) is not involved in fermentation as it is an anaerobic process.
5. Conclude that NAD+ is always a product of fermentation: Regardless of the specific type of fermentation, the regeneration of NAD+ is essential for the continuation of glycolysis and energy production in the absence of oxygen.