Human beings depend on oxygen to sustain life. However, at the cellular level, muscle cells are A) aerobics B) strict anaerobes C) capable of alcoholic fermentation D) facultative anaerobes

The correct answer is D) facultative anaerobes.

Muscle cells are facultative anaerobes, meaning they primarily use aerobic respiration to generate energy when oxygen is available, but they can switch to anaerobic processes, such as lactic acid fermentation, when oxygen levels are low. This adaptability allows muscle cells to continue producing energy during intense exercise when oxygen supply may not meet the demand.