The human body can tolerate only a small range of temperature, especially when the per- son is engaged in vigorous activity. Heat reac- tions usually occur when large amounts of water and/or salt are lost through excessive sweating following strenuous exercise. When the body becomes overheated and cannot elim- inate this excess heat, heat exhaustion and heat stroke are possible. Heat exhaustion is generally characterized by clammy skin, fatigue, nausea, dizziness, profuse perspiration, and sometimes fainting, resulting from an inadequate intake of water and the loss of fluids. First aid treatment for this condition includes having the victim lie down, raising the feet 8 to 12 inches, applying cool, wet cloths to the skin, and giving the victim sips of salt water (1 teaspoon per glass, half a glass every 15 minutes) over a 1-hour period. Heat stroke is much more serious; it is an immediate life-threatening situation. The char- acteristics of heat stroke are a high body temper- ature (which may reach 106° F or more); a rapid pulse; hot, dry skin; and a blocked sweating mechanism. Victims of this condition may be unconscious, and first-aid measures should be directed at quickly cooling the body. The victim should be placed in a tub of cold water or repeat- edly sponged with cool water until his or her temperature is sufficiently lowered. Fans or air conditioners will also help with the cooling process. Care should be taken, however, not to over-chill the victim once the temperature is below 102° F. Which of the following is a symptom of heat exhaustion?