Which of the following is a common sign of infection?

Fever is a common sign of infection because it indicates that the body's immune system is responding to an invading pathogen, such as bacteria or viruses. When an infection occurs, the body's temperature-regulating center in the hypothalamus raises the body's temperature, leading to fever. This increased temperature helps to create an environment that is less hospitable to pathogens and also enhances the effectiveness of immune responses, such as the activity of white blood cells.

While high blood pressure, extreme fatigue, and sweating can be associated with various medical conditions, they are not as specific or consistent indicators of infection as fever. For instance, high blood pressure can have multiple causes unrelated to infection, and extreme fatigue may result from many factors including stress, lack of sleep, or other health issues. Sweating can be a response to fever or physical exertion and is not solely indicative of infection. Thus, fever stands out as a more definitive sign of the body’s response to infection.