Final answer:
The third stage of the body's response to stress is known as the stage of exhaustion.
Step-by-step explanation:
The third stage of the body's response to stress, according to Dr. Hans Selye, is known as the stage of exhaustion. During this stage, the body's ability to resist becomes depleted as physical wear takes its toll on the body's tissues and organs. This can lead to illness, disease, and even death.