Tom has been working hard on a project for his employer. The project is winding down now and he has recently started exhibiting a very expansive mood, is quite talkative, and reports that he really does not feel the need to sleep much. However, he soon starts to show signs that his mood is somewhat depressed; he also reports that he does not have much interest in his normal activities and that he has gained quite a bit of weight over a short period of time. On the basis of this information, you might diagnosis Tom with:_______

a. unipolar depression.
b. bipolar disorder I (BP-I).
c. bipolar disorder II (BP-II).
d. mixed bipolar disorder.