Fever results from the stimulations of the hypothalamic thermoregulatory center by: A prostaglandins B granuloma C opsonin D All of the above

A prostaglandins

Explanation:

Fever is the abnormal body temperature that is caused by pyrogens.Pyrogens  are the chemicals produced by pathogen. Fever is protective mechanism of body to fight against pathogens. It is actually the immune response that spread to whole body with elevated temperataure. The elevated temperature helps to deal with pathogen more efficiently.

The interleukins released be immune cells in response pyrogen ultimately lead to release of prostaglandin E2. Prostaglandin E2 reset the hypothalamus thermoregulation. The hypothalamus feels the body temperature is cool although how high is the body temperature.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: