Jaina just got home from a difficult workout. She is complaining of muscle soreness and cramps. Which waste product of fermentation caused the soreness and cramps?

During intense exercise, muscle cells may not get enough oxygen for aerobic respiration, so they use lactic acid fermentation. This process produces lactic acid, which is associated with the soreness and cramps described. Therefore, the correct choice is lactic acid.

AI-written and checked against the verified answer.