Which of the following can be a common sign of dehydration?

Dry mouth and fatigue are indeed common signs of dehydration. When the body lacks sufficient fluids, one of the first indicators is often a dry mouth, which occurs because saliva production decreases. This dryness can make it uncomfortable to swallow and may lead to a feeling of thirst. Fatigue is another prevalent symptom, as dehydration can reduce blood volume, impacting overall energy levels and causing tiredness. These signs serve as important reminders for lifeguards and individuals alike to ensure proper hydration, especially in a hot climate or during physical exertion, such as swimming or surfing. Recognizing these signs can aid in taking timely action to rehydrate and prevent further complications associated with dehydration.

The other choices, while they may represent alternative states, do not reflect dehydration. Feeling energetic typically indicates sufficient hydration and well-being, increased appetite may suggest adequate nutrition and hydration, and bright and clear urine usually signifies proper hydration levels.