How does fever indicate that your body's immune system is doing its job?
a. fever increases white blood cell production.
b. fever raises the body's temperature to destroy harmful substances.
c. fever triggers inflammation.
d. fever causes the secretion of hormones that fight harmful substances.

Fever raises the body's temperature to destroy harmful substances. (Option B)

Explanation: Fever also called pyrexia is one of the most common complains in the medical practice. It is defined as the body temperature that is above normal range (for that individual) without any physiological cause to it. This is usually above 38 degree Celsius recorded by the thermometer .

When body suffers from certain pathological process namely “inflammation” certain chemicals are released in the body called pyrogens e.g. which is interleukin-2. white blood cell called  macrophage is also activated, and the body temperature rises which indicates that the immune system is doing its job.

protist eukaryotes that are not plants, animals, or fungi ("misfits")

b a mature ovary of a plant.