Pneumothorax related to diving is most commonly caused by which of the following?

The most common cause of pneumothorax related to diving is holding breath during ascent. When a diver ascends while holding their breath, the air in their lungs expands due to the decreasing pressure. This expansion can exceed the capacity of the lung tissue, leading to a rupture and causing air to escape into the pleural space, resulting in a pneumothorax.

Understanding this concept emphasizes the importance of equalizing pressure and exhaling properly during ascents to allow for the safe displacement of air from the lungs. This preventative measure is vital for avoiding the severe consequences that can arise from a pneumothorax.

Other options, such as rapid descents or going too deep, primarily relate to issues such as barotrauma or decompression sickness rather than directly causing pneumothorax. Sudden temperature changes can affect a diver's physiology, but they are not a primary cause of pneumothorax associated with diving.