Which cell type, molecule, or process listed below does not have a function or rolein both the innate and adaptive immune systems?

These mechanisms together with phagocytosis, antimicrobial peptides called defensins, and the complement system. Jawed vertebrates, including humans, have even more unusual defense mechanisms, including the ability to adapt over time to recognize specific pathogens more efficiently. This process was got by  immunity is the basis of vaccination. 

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.