Final answer:
The third stage of the general adaptation syndrome is characterized by exhaustion, which occurs after the body's resources are depleted from prolonged stress.
Step-by-step explanation:
The third stage of the general adaptation syndrome (GAS) is characterized by exhaustion. GAS represents a three-phase process initiated by stressors: an initial alarm reaction, a period of resistance, and eventually exhaustion. During the alarm reaction, the body undergoes the fight-or-flight response. If the stressor persists, the organism adapts and enters the stage of resistance, where physiological reactions diminish in intensity. However, with prolonged or repeated stress, the organism reaches the final phase, the stage of exhaustion, where the body's resources become depleted, potentially leading to health problems such as hypertension and coronary artery disease.