Nina has the flu and a high fever. Her immune system is exhibiting the third line of defense. This defense is part of adaptive immunity.

False.

Explanation:

The fever that Nina presents is caused by the body's second line of defense, which represents innate immunity, which is the one that is born with the individual.

The immune system's first line of defense concerns the body's physical barriers. The second line of defense hurts the action of leukocytes, which are cells that fight inflammation and can cause reactions such as high fever, hunting pain, sneezing, among others. The third line of defense refers to the action of lymphocytes and antibodies produced by the body.

These three lines represent defenses that already exist naturally within the human body and for this reason are part of innate immunity.