Which of the following methods should you use to extend breath-hold time?

To extend breath-hold time effectively and safely, it's essential to focus on proper breathing techniques that enhance oxygen utilization without causing physiological stress. The choice to never hyperventilate is grounded in the understanding of how oxygen and carbon dioxide levels in the body work. Hyperventilation reduces carbon dioxide levels, leading to a longer period before the urge to breathe is felt. However, this can result in shallow water blackout due to the body's instinctive response being suppressed, potentially causing a serious risk if one becomes unconscious underwater.

Instead, engaging in breathing exercises can improve one’s lung capacity, enhance overall breathing efficiency, and condition the body to manage carbon dioxide more effectively. Taking short, shallow breaths does not stimulate lung capacity and would likely decrease breath-hold duration rather than extend it. Prioritizing safe breathing practices and enhancing lung function through proper techniques is key to improving breath-hold time while ensuring the diver's safety.