Which of the following is a common sign of dehydration?

Dry mouth is a common sign of dehydration because the body lacks adequate fluids to maintain normal saliva production. When fluid intake is insufficient, the mucous membranes in the mouth can become parched, leading to a sensation of dryness. This symptom can arise alongside other signs of dehydration, such as thirst and reduced urine output.

In contrast, bright skin typically suggests good hydration and health. Frequent urination is more often associated with adequate hydration or conditions like diabetes mellitus, rather than dehydration. Increased energy levels are generally not linked with dehydration, as a lack of fluids often results in fatigue and lethargy instead. Recognizing dry mouth as a sign of dehydration is important for timely intervention and treatment.