Introversion and extraversion result from

A) failures or successes in college.
B) both genetic and environmental influences.
C) resolution of the complexes into psychological types.
D) genetics entirely.

Both genetic and environmental influences play a role in the development of introversion and extraversion. Twin studies have shown that there is a genetic component to these traits, but environmental factors such as upbringing and life experiences also play a role in shaping personality. The resolution of complexes into psychological types (choice C) is a concept from Jungian psychology, which is one perspective on understanding personality, but it is not the most widely accepted explanation for introversion and extraversion. Choice A is not accurate as there is no evidence to suggest that college success or failure is related to introversion or extraversion. Choice D is also not accurate as although genetics do play a role in personality development, it is not the sole determinant.