It is either carcinogens or viruses (I think the first) I hope this helps!
The answer is Vaccination.
Acquired or adaptive immunity is the body's third line of defense. This is protection against specific types of pathogens. Acquired immunity may be either natural or artificial in nature. Both natural and artificial immunity have passive and active components. Active immunity results from an infection or an immunization, while passive immunity comes from naturally or artificially gaining antibodies.
Um..? okay?..
“This Question has been deleted”?
Answer:
Nitrogen is the most commonly limiting nutrient in plants. Legumes use nitrogen fixing bacteria, specifically symbiotic rhizobia bacteria, within their root nodules to counter the limitation. Rhizobia bacteria convert nitrogen gas (N2) to ammonia (NH3) in a process called nitrogen fixation.