Endogenous pyroge: a) is released by infection-fighting leukocytes and acts on muscle tissue. b) is released by the hypothalamus and acts on infection-fighting leukocytes. c) is released by infection-fighting leukocytes and has the same action as aspirin. d) is released by infection-fighting leukocytes and acts on the temperature-integrating centers of the hypothalamus. e) is released by the pyloric region of the stomach and raises the temperature of digestion.

d) is released by infection-fighting leukocytes and acts on the temperature-integrating centers of the hypothalamus.

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.