Fever occurs due to -

Ans. is 'a' i.e., IL1 Pyrogeneso Pyrogenes are substances that cause fever.o Pyrogens may be exogenous or endogenous* Exogenous- Bacterial toxins* Endogenous- IL0-l,TNF-a, IL-6, Interferons, Cilioiy's neurotropic factoro These pyrogenes increase the level of PGE2 in the hypothalamus that elevates the thermoregulatory set point and causes fever.