In Biological Trait Theory, the Important Difference Between Extraverts and Introverts

In biological trait theory, the important difference between extraverts and introverts is that

A) extraverts are overaroused, whereas introverts are underaroused.
B) extraverts desire more arousal, whereas introverts try to avoid it.
C) introverts seek arousing environments, whereas extraverts seek calm environments.
D) the resting level of the reticular activating system RAS) is high in extraverts and low in introverts.