Answer:
d) is released by infection-fighting leukocytes and acts on the temperature-integrating centers of the hypothalamus.
Step-by-step explanation:
Endogenous pyrogens are a type of pyrogen known to induce fever. This pyrogen is a low molecular weight pyrogen referred to cytokines, which is released from monocyctes in the presence of an antigen like bacteria. In the presence of an antigen or during infection, they stimulate chemical responses that leads to fever.
Endogenous pyrogens act on the temperature-integrating centers of the hypothalamus, which then cause the hypothalamus to increase the body temperature to exceed the normal range and then causing a fever. It also stimulate the immune cells to fight infections
Examples of endogenous pyrogens are interleukin - 1, interferon -alpha, tumor necrosis factor etc.