What is the product of anaerobic respiration in animals?

The product of anaerobic respiration in animals is lactic acid. During anaerobic respiration, which occurs when oxygen supply is low, glucose is broken down to produce energy. However, instead of fully oxidizing glucose all the way to carbon dioxide and water as in aerobic respiration, the process generates lactic acid as a byproduct. This is particularly relevant in muscle cells during intense exercise when oxygen is scarce. The accumulation of lactic acid can lead to muscle fatigue and discomfort.

In contrast, glucose is a reactant in this process rather than a product, and oxygen is not produced because anaerobic respiration occurs in the absence of it. Carbon dioxide is typically produced during aerobic respiration, not anaerobic. Therefore, lactic acid is accurately identified as the correct answer, as it is the direct byproduct of the energy generation during anaerobic conditions in animal cells.