Which symptom is caused by severe dehydration?

Severe dehydration can lead to a range of physiological changes in the body, one of which is muscle cramping. This occurs because dehydration disrupts the balance of electrolytes—such as sodium, potassium, and calcium—that are necessary for muscle function. When these electrolytes are out of balance, muscles can become irritable and more prone to cramping.

In contrast, the other options are typically associated with hydration or well-being rather than dehydration. Increased motivation and enhanced cognitive performance are usually promoted by adequate hydration and overall fitness, while dehydration would likely lead to lethargy and cognitive impairments. Similarly, the perception of having more energy is usually linked to being well-hydrated, as dehydration can lead to feelings of fatigue and weakness. Thus, muscle cramping is the clear symptom associated with severe dehydration due to its impact on muscle and electrolyte balance.