The Focus on Neuroscience Box "The Neuroscience of Personality: Brain

The Focus on Neuroscience box "The Neuroscience of Personality: Brain Structure and the Big Five" describes an MRI study that investigated whether personality traits are associated with differences in brain structure. What was a major conclusion of this study?

A) Preliminary findings suggest that there are biological influences on personality; however, the findings are correlational.
B) There were no major differences in brain structure between people who differ in personality traits.
C) Although there might be differences in brain structure patterns in people with different personality traits, these differences are too subtle to be measured with current neuroscience techniques.
D) Extraversion is associated with greater volume in the frontal cortex, while neuroticism is associated with greater volume in the medial cortex.