What happens after the second time you are exposed to a pathogen?

A. The body will not be able to fight off the pathogen quickly, because it knows how to get into the body easier.

B. The body’s immune system will react the same was as it did during the first exposure.

C. The body can only be exposed to a pathogen a second time if you do not have a vaccine.

D. The body will know how to fight off the pathogen quickly, because memory cells have been created after the first encounter.