Dr. Wren is in the process of diagnosing Lily's psychological disorder. After asking Lily a few questions about her symptoms, Lily reveals that she experiences alternating episodes of euphoria and distress. On some days, Lily claims that she feels like she is capable of doing anything in the world. During this phase, she can't sleep; feels restless, and is extremely excitable. On the other days, Lily feels utterly worthless and miserable. During this phase, Lily lies in bed all day and is troubled by morbid thoughts. In the context of disorders involving emotion and mood, it can be inferred that Dr. Wren is likely to diagnose Lily with:A. major depressive disorder. B. obsessive-compulsive disorder. C. bipolar disorder. D. schizophrenia.