Answer: because stem cells make different antigen receptors depending on the invading microorganism.
Explanation:
The immune system is a host defense system comprising many biological structures and processes within an organism that protects against disease.
Therefore, to function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.
Diversifying, because Maggie is trying to get a person from Brazil, to play on the soccer team that will most kill probably have people from where she is from.
