Question

when would our muscle cells use lactic acid fermentation?
when there is a lot of oxygen flowing to cells because of lack of exercise.
during periods of strenuous exercise when there is a lack of oxygen being delivered to cells.

Explanation:

Lactic acid fermentation in muscle cells occurs when oxygen supply is insufficient, typically during strenuous exercise (as muscles need more energy, and if oxygen can't meet the demand, fermentation is used). The first option is incorrect because abundant oxygen would support aerobic respiration, not fermentation.

Answer:

During periods of strenuous exercise when there is a lack of oxygen being delivered to cells.