Final answer:
The correct answer is option c. In the stage of exhaustion, there is breakdown of internal organs and weakening of the immune system in the general adaptation syndrome.
Step-by-step explanation:
The breakdown of internal organs and weakening of the immune system occur in the stage of exhaustion in the general adaptation syndrome.
During this stage, if the stress continues for a longer term, individuals may suffer from symptoms such as depression, suppressed immune response, severe fatigue, or even a fatal heart attack.
The symptoms during the stage of exhaustion are mediated by the hormones of the adrenal cortex, especially cortisol, released as a result of signals from the HPA axis.