Which of the following is a common practice to avoid oxygen toxicity during dives?

Limiting bottom time on deeper dives is a crucial practice to avoid oxygen toxicity during dives. Oxygen toxicity occurs when divers are exposed to high partial pressures of oxygen, which become more significant at greater depths. As the depth increases, the partial pressure of oxygen in a dive mix also increases, which can elevate the risk of central nervous system (CNS) toxicity.

By restricting the duration of time spent at increased depths, divers can manage their exposure to high levels of oxygen more effectively. This practice allows divers to minimize the total amount of oxygen breathed at partial pressures that could lead to toxicity symptoms, such as visual distortions, convulsions, or other neurological effects.

The other choices do not effectively address the risk of oxygen toxicity in the same way. For example, increasing dive depths could actually raise the risk of toxicity, while ascending without planning risks not allowing for proper decompression, which is unrelated to oxygen toxicity but pertains to overall dive safety. Using surface-supplied air, while beneficial in certain situations, does not directly correlate to managing oxygen toxicity as compared to the practice of limiting bottom time.