Final answer:
Pyruvic acid is not an end product of fermentation; it is a substrate that gets transformed during the fermentation process into products like ethanol, carbon dioxide, or lactic acid, depending on the type of fermentation.
Step-by-step explanation:
The end products of fermentation depend on the type of fermentation process that occurs. In alcoholic fermentation, which is commonly associated with yeasts and some bacteria, the end products are ethanol and carbon dioxide. The first chemical reaction in this process involves the conversion of pyruvic acid into these products. Pyruvic acid is the key reactant in fermentation that is also shared by aerobic respiration but is not itself an end product of fermentation.
In the case of lactic acid fermentation, such as that occurring in animal skeletal muscles, the end product is lactic acid. Considering the options provided in the question, Pyruvic acid (A) is not an end product of fermentation, but rather a substrate that is transformed during the fermentation process.
Therefore, the correct answer to the question is A) Pyruvic acid.