Heat exhaustion is primarily due to the loss of which substances?

Heat exhaustion occurs when the body loses a significant amount of fluids and electrolytes due to prolonged exposure to high temperatures or excessive physical exertion in hot environments. This condition is characterized by dehydration, which primarily results from excessive sweating. Along with water, the body also loses important electrolytes, especially sodium, through sweat.

Sodium is crucial for maintaining fluid balance in the body and is involved in nerve function and muscle contractions. When heat exhaustion occurs, both water and sodium levels drop, which can lead to symptoms like weakness, dizziness, excessive sweating, and nausea.

While the body also loses other electrolytes, such as potassium and magnesium, during sweating, the combination of sodium and water loss is primarily what leads to the condition of heat exhaustion. Therefore, recognizing that both substances play a critical role in the development of this heat-related illness makes the answer that includes both sodium and water the most appropriate choice.