Which of the following is a sign that a diver may need immediate medical attention?

Confusion or disorientation in a diver is a critical sign that may indicate a serious underlying issue, such as nitrogen narcosis, hypoxia, or other medical conditions that could severely impair a diver's cognitive abilities and decision-making skills. If a diver is expressing confusion or is disoriented, it suggests that their mental state is compromised, which can lead to dangerous situations both underwater and after surfacing. Immediate medical attention is essential to address these symptoms and prevent potential accidents or further complications.

In contrast, minor skin irritation might not warrant urgent medical response unless it escalates. Casual use of air pertains more to a diver's consumption rates rather than their immediate health status. The ability to swim unaided indicates that the diver is still functioning and capable, which doesn't necessarily mean they are in need of immediate medical attention. Ultimately, confusion or disorientation should always be treated seriously in the context of diving.