What defines major depression according to its duration and symptoms?

Major depression is characterized by a specific set of symptoms and a duration that typically lasts for at least two weeks. The diagnosis relies on the presence of multiple symptoms, such as persistent sadness, loss of interest or pleasure in activities, changes in appetite or weight, sleep disturbances, fatigue, feelings of worthlessness, diminished ability to think or concentrate, and recurring thoughts of death or suicide.

The correct answer reflects that major depression's duration is usually at least one to two weeks, aligning with clinical guidelines that emphasize the necessity of multiple symptoms occurring simultaneously to support a diagnosis. This extended timeframe allows for observation of the significant impact these symptoms can have on an individual's daily functioning, which is crucial for distinguishing major depression from transient mood fluctuations.

In contrast, options regarding a duration of less than a week or requiring only one symptom do not meet the established criteria for major depression, as these conditions would not reflect the severity and persistence required for diagnosis. Moreover, having major depression always accompanied by mania describes a different mood disorder called bipolar disorder, which is not applicable in this context. Thus, understanding the specific requirements and symptomatology of major depression is essential for accurate identification and effective treatment planning.