Which feature defines a psychotic depressive disorder?

A psychotic depressive disorder is primarily characterized by the presence of hallucinations or delusions, which are indicative of psychosis. In this context, psychosis refers to a disconnection from reality, resulting in symptoms such as false beliefs (delusions) or perceptual disturbances (hallucinations) that occur alongside the depressive symptoms. This condition signifies a more severe form of depression, often requiring different treatment approaches compared to non-psychotic depression.

The other options reflect features that do not align with the essential characteristics of a psychotic depressive disorder. Reactive mood suggests a situational trigger for depression, which does not encompass the psychotic element. Complete immobility could occur in various contexts, such as in severe depression or catatonia, but it is not a defining feature of psychotic depressive disorder. Excessive energy levels are more characteristic of mania or hypomania, which are not typical of depressive disorders. Thus, the defining aspect of this disorder is indeed the presence of hallucinations or delusions.