Based on our discussion of microbial community transplantation, which of the following statements is most true?
a. Transplanted microbial communities can confer beneficial traits, such as pathogen resistance, to the host.
b. All microbial transplantations lead to increased instances of autoimmune diseases.
c. Transplanted communities decrease the host's lifespan.
d. Transplantation primarily introduces harmful pathogens to new sites.