What symptom indicates that a diver might be suffering from heat stroke?

A rapid heart rate is a significant symptom of heat stroke, indicating the body's attempt to manage the elevated core temperature. When a person's body overheats, the cardiovascular system responds by increasing heart rate to enhance blood flow to the skin, facilitating heat dissipation. In cases of heat stroke, the body can no longer regulate its temperature effectively, resulting in symptoms such as confusion, altered mental state, and a rapid pulse.

The other symptoms provided do not accurately correlate with heat stroke. Cold and clammy skin or excessive shivering would typically be more associated with hypothermia, while hyperventilation is more often a response to anxiety or other conditions rather than heat stroke. Recognizing the correct symptoms and their implications is crucial in a diving context, as timely intervention is necessary for effective treatment.