Regarding the assertion and reason, select the right option:
Assertion [A]: Vaccination exploits the fact that the immune system’s response to a second exposure to pathogens is much faster and more vigorous than it is the first time around.
Reason [R]: Vaccines mimic live pathogens.
Both A and R are true and R explains A
Vaccine is a biological preparation that contains weakened or dead versions of a pathogen that still displays all the antigens but do not cause the disease. Our immune system generates memory cells in response to the pathogen. An encounter with the live pathogen therefore, is perceived by our immune system as a second encounter and triggers a more intensified and quick response, thereby, saving us from the infection.