Vaccines prevent disease by
a. bringing bacteria to infect healthy cells.
b. containing specific t lymphocytes.
c. combining with pathogens to inactivate them.
d. preparing the immune system to recognize and destroy pathogens.

The nature–nurture issue refers to the debate over the relative contributions that make to the development of psychological traits. a.introspection and nerve cell activity b.unconscious and conscious motives c.behavior and mental processes d.genes and experience