In the absence of sufficient oxygen, our muscle cells undergo anaerobic respiration. In this process, glucose is partially broken down to form lactic acid and a small amount of energy is released. This lactic acid accumulates in muscles, causing pain and fatigue after heavy exercise. When enough oxygen becomes available, lactic acid is converted back to carbon dioxide and water. Thus, the correct answer is that lactic acid and energy are produced during anaerobic respiration in human muscle cells. The correct option is (B).