Sam was deeply depressed for weeks. After a few weeks of relative normal function, he now has an extremely elevated mood. He sleeps very little, believes that all of his ideas are brilliant and is easily angered when anyone disagrees with him. He is spending money without concern for the great debt he is accumulating. Sam most likely has:

a. major depressive disorder

b. narcissistic personality disorder

c. dissociative identity disorder

d. bipolar disorder

d. Bipolar disorder

Explanation:

In psychology and psychopathology and according to the DSM-V the bipolar disorder is a mental disorder that causes shifts in mood and activity levels in a clear pattern that is described in the next paragraph:

When a person has this disorder, the person can have extreme changes like going from extremely energized behavior followed by episodes where they feel really "down", sad and depressed.

In this example, Sam is first depressed for weeks, but then, after some weeks of feeling normal and acting "normal", he now has an elevated mood and sleeps very little and believes his ideas are brilliant, we can see that he is now in a period of high energy after those weeks feeling depressed. Thus, he most likely has bipolar disorder.