Edith, a 45-year-old journalist, alternates between extreme sadness and lethargy and extreme euphoria and overactivity. the drug most likely to prove beneficial to her is:
a) lithium.
b) valium.
c) clozaril.
d) thorazine.

A - Lithium.

Explanation:

Given the symptoms of Edith, who alternates between extreme sadness and extreme euphoria, maybe caused by a bipolar disorder or Dissociative identity disorder (DID), would be most beneficiated by lithium, which is used to treat manic episodes such as manic depression, bipolar disorder, or manic symptoms such as mood swings, aggression or anger, etc. This drug helps reduce the frequency of this episodes.