Question

the main, or central, idea of the passage is fevers are useful because they help the body fight infections. how does the detail in bold develop the main idea? fevers can be uncomfortable, but the upside is that they are evidence of the bodys attempt to heal. when a person develops an infection, a section of the brain called the hypothalamus recognizes a threat. the hypothalamus responds by increasing the bodys temperature. since both viruses and bacteria are temperature sensitive, this environment helps prevent them from multiplying. in addition, scientists have found evidence that fevers may increase the number of certain lymphocytes—white blood cells that are part of the immune system. increased lymphocytes make the body more effective in destroying infected cells. of course, this doesnt mean that high fevers dont warrant medical treatment. in fact, another reason that fevers are beneficial is that they serve as warning signs, indicating that something is amiss. it describes one manner in which fevers fight infections. it explains the function of lymphocytes in great detail. it points out a weakness of the fever response.

Explanation:

The bold - faced detail states that fevers may increase lymphocytes which help destroy infected cells, thus describing a way fevers fight infections. It doesn't focus on lymphocyte function in general or point out a fever response weakness.

Answer:

It describes one manner in which fevers fight infections.