Final answer:
A nurse showing signs of depression due to prolonged stress is exhibiting an emotional response to stress.
Step-by-step explanation:
The clinical manifestations of depression experienced by a nurse under prolonged stress reflect the emotional component of stress. Stress triggers a range of responses, including physiological, cognitive, and behavioral reactions, but when stress becomes chronic, it can lead to serious health consequences including psychological disorders such as depression. In the context of the provided options, while depression can also have physical and mental components, it is fundamentally an emotional response to prolonged stress.