Amy has had several periods of extremely "up" moods. They last for a couple of weeks, and she has gotten into trouble several times. During these periods, she doesn't sleep, spends way too much money, gets involved in bad business decisions, talks quickly and thinks even more quickly, and believes she can do anything. The best diagnosis for Amy is __________.

A. manic disorder
B. bipolar II disorder
C. bipolar I disorder
D. cyclothymic disorder

Answer: C