Final answer:
In Selye's General Adaptation Syndrome, Christy's reserves would be diminished in the stage of exhaustion, which is the third and final stage where prolonged stress results in depleted physical and mental resources leading to potential health crises.
Step-by-step explanation:
Christy, as a police officer experiencing extreme stress, would find her reserves being diminished in the stage of exhaustion, which is the third stage of Selye's General Adaptation Syndrome (GAS). In this stage, the body's ability to resist stress has been worn down by prolonged exposure to the stressor.
At this point, the body's physical and mental resources are critically depleted, which can lead to a range of serious health problems, such as depression, immune suppression, severe fatigue, or even a heart attack.
These symptoms are controlled by hormones like cortisol from the adrenal cortex due to prolonged activation of the HPA axis. This stage contrasts with the initial vigilance and subsequent adaptation characterized by the alarm reaction and stage of resistance, respectively. The stage of exhaustion emerges after the body can no longer maintain homeostasis in the face of continuous stress.