The Exact Cause of Bipolar Disorder Has Not Been Determined;

The exact cause of bipolar disorder has not been determined; however, for most patients, which of the following is true?

A) Several factors, including genetics, are implicated.
B) Brain structures were altered by stress early in life.
C) Excess sensitivity in dopamine receptors may trigger episodes.
D) Inadequate norepinephrine reuptake disturbs circadian rhythms.