27 A 45-year-old woman with multiple sclerosis was treated with interferon beta-1a six months ago, which resolved her physical symptoms. The client admits this was a difficult time for her and she had to make a lot of adjustments in her life. She had to quit her job; after doing so she got behind on her bills. She reports her life was great before the multiples sclerosis diagnosis. She now presents with depressed mood (experienced daily for the past several months), middle insomnia (of recent onset), poor appetite, trouble concentrating, and lack of interest in sex. Although she has no physical symptoms, she is frequently absent from work. She denies any active plans to commit suicide but admits that she often thinks about it, as her mood has worsened. What is the most likely diagnosis? A: Major depressive disorder. B: Persistent depressive disorder (dysthymia). C: Depressive disorder due to another medical condition. D: Substance/medication-induced depressive disorder.