Final answer:
Naturally acquired active immunity is when the body develops immune protection after being exposed to a pathogen. Memory B cells and memory T cells are formed during the initial infection, providing long-term immunological memory.
Step-by-step explanation:
Naturally acquired active immunity is when the body develops immune protection after being exposed to a pathogen. This type of immunity is a result of the immune system's response to an infection. Memory B cells and memory T cells are formed during the initial infection, which provide long-term immunological memory of the pathogen. If the same pathogen tries to infect the body again in the future, the immune system is able to mount an immediate response due to the presence of these memory cells.