Which of the following is a sign that a diver should ascend?

Feeling dizzy or disoriented is a critical indicator that a diver should ascend. Such symptoms can be signs of nitrogen narcosis or other pressure-related issues, which can compromise a diver's ability to make sound decisions and perform safely underwater. When a diver experiences dizziness, it may indicate that they are becoming adversely affected by the depth or have encountered other physiological issues. Ascending to a shallower depth is essential for addressing these symptoms and ensuring the diver's safety.

In contrast, simply observing aquatic life or experiencing a pleasant sensation does not warrant an ascent on its own, as these experiences are part of the diving environment and do not indicate a health concern. Completing the bottom time is similar; while it may suggest it’s time to ascend based on a dive plan, it is not an immediate sign related to the diver’s condition. Safety protocols prioritize bodily signals, like dizziness, which can indicate a need for immediate action.