Why might a diver choose to use Nitrox instead of regular air?

A diver might choose to use Nitrox instead of regular air because Nitrox is a gas mixture where the percentage of oxygen is higher than that in regular atmospheric air, leading to several advantages suited for different diving situations. One significant benefit is the reduced nitrogen content in Nitrox, which can decrease the overall nitrogen absorption during a dive. This ultimately can allow for longer bottom times without increasing the risk of nitrogen narcosis and decompression sickness.

By decreasing nitrogen absorption, Nitrox enables divers to spend more time at greater depths and still maintain safe dive profiles, which is particularly beneficial for technical diving where extended bottom times or deeper dives are more common. Additionally, the higher oxygen content in Nitrox can reduce the risk of narcotic effects that occur at higher pressures with regular air—thus enhancing mental clarity during dives.

Each of these advantages highlights why a diver might opt for Nitrox over regular air, making the choice of "all of the above" an appropriate answer as it encompasses the various benefits that Nitrox provides in different diving contexts.