Which of the following is a sign of hypothermia?

Hypothermia occurs when the body loses heat faster than it can produce it, leading to a dangerously low body temperature. A slow, irregular heartbeat is a characteristic sign of hypothermia. When the body temperature drops significantly, the heart rate decreases, which can sometimes become irregular due to the stress placed on the body and the impact on the heart's electrical system. This can ultimately lead to dangerous complications if not addressed.

In contrast, the other options do not align with the physiological responses expected in hypothermia. Typically, you would not see an elevated body temperature in someone experiencing hypothermia, as their body is unable to maintain warmth. Rapid heartbeat may occur in other medical conditions but is not typical for hypothermia, as the body usually responds with bradycardia, or a slowed heart rate. Increased sweating is also generally not associated with hypothermia; rather, a hypothermic individual may be shivering or have minimal perspiration as the body tries to conserve heat.