Final answer:
The primary symptom of heat stroke is hot, dry skin. This is due to the body's cooling mechanisms, such as dilated blood vessels and sweating, struggling to handle the extreme heat. Other mentioned symptoms are more relevant to less severe heat-related issues.
Step-by-step explanation:
The common sign or symptom of heat stroke is a. Hot, dry skin. In the body's response to excess heat, the blood vessels dilate which allows for heat loss to the environment. When this is insufficient, sweat glands secrete fluid as a secondary measure. As this sweat evaporates, it aids in cooling the body.
However, in a state of heat stroke, the body's cooling mechanisms can't keep up with the heat, causing symptoms such as hot, flushed, dry skin because there is little sweat left. Profuse sweating, mentioned as one of the symptoms, is more common in heat exhaustion, a less severe condition than heat stroke. Options c, d and b are not commonly associated with heat stroke.
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