Final answer:
Pyrogens trigger the hypothalamus to reset the body’s temperature set point higher, causing a fever; it’s a defensive response to infection.
Therefore the correct answer is option is C) Pyrogens cause the hypothalamic thermostat to reset to a higher range.
Step-by-step explanation:
The statement that best describes the function of pyrogens is C. Pyrogens cause the hypothalamic thermostat to reset to a higher range, resulting in fever. Pyrogens are chemicals that are released into the blood when bacteria are destroyed by phagocytic leukocytes.
These pyrogens then circulate to the hypothalamus, which is the body's thermostat, and signal it to increase the body's set point for temperature. This triggers a fever, which is a defense mechanism of the body and can help impair the reproduction of bacteria and the activity of viruses, as well as increase the effectiveness of the body’s immune cells.