Compared to a few decades ago, personality psychologists today are much more likely to acknowledge the importance of biological influences on personality. This shift is partly due to:___.
a. the overwhelming influence of the trait model in personality psychology.
b. the increase in researchers with MD's getting into the field of personality research.
c. the increasing use of twin studies in all personality research improvements.
d. in research instruments that allow researchers to assess personality and biology more accurately.