Question

fill in the blank question
the line of defense that leaves the body with a memory of a pathogen is the
line of defense.

Explanation:

The body has three lines of defense. The first two (physical/chemical barriers, non - specific immune cells) are non - specific. The third line of defense involves the immune system's adaptive response (like B and T cells), which creates memory cells to remember pathogens for faster future responses.

Answer:

third