What does the term "controlled ascent" mean?

The term "controlled ascent" refers to ascending at a gradual rate to prevent lung expansion injuries. When divers ascend, the pressure around them decreases, and if they rise too quickly, the expanded gases in their lungs can cause serious injuries, such as air embolism or lung over-expansion. A slow and deliberate ascent allows the body to adjust to the reducing pressure, enabling safe gas exchange and preventing injuries.

While the other options discuss various aspects of diving, they do not align with the definition of a controlled ascent. Rapid ascent could lead to complications and is advised against for safety reasons. Floating upward without making any adjustments lacks control and could also lead to improper ascent rates. Lastly, maintaining a constant depth is more related to techniques used during underwater exploration rather than ascent. Thus, the emphasis on a gradual ascent is crucial for diver safety and health.