Because Greta is an extravert, she frequently goes to parties where she is encouraged to laugh and socialize with her friends. Because Jim is an introvert, he frequently spends weekends in the library where it's easy to quietly reflect and study. Greta and Jim best illustrate what is meant by: A) an external locus of control. B) reciprocal determinism. C) the self-serving bias. D) the Barnum effect.