Which of the following is NOT a symptom of dehydration?

In the context of dehydration, increased saliva production is not a typical symptom. When an individual is dehydrated, their body often struggles to maintain normal functions due to the lack of adequate fluids. Consequently, one of the body's responses to dehydration is to conserve moisture, often leading to reduced saliva production rather than an increase.

The other symptoms listed are indeed common indicators of dehydration. Sunken eyes are a visible sign of fluid loss, as the tissues around the eyes lose hydration and elasticity. Excessive sweating, while it might sound contradictory, can indicate that the body is attempting to cool down without sufficient fluids, which can lead to dehydration if fluids are not replenished. Additionally, concentrated urine is a direct result of the kidneys conserving water—when the body is dehydrated, urine becomes darker and more concentrated as the body retains fluid.

Therefore, the correct answer points to the symptom that does not align with the physiological responses associated with dehydration.