Final answer:
Nerves can indirectly affect organs during stress by stimulating the adrenal gland, which releases adrenaline and norepinephrine under the regulation of the sympathetic nervous system and hypothalamus, thus initiating the fight-or-flight response. Therefore, the correct option is b.
Step-by-step explanation:
In the reaction to fearful and stressful situations, nerves may indirectly affect organs by stimulating the adrenal gland. During a stress response, the sympathetic nervous system is activated, which then prompts the adrenal medulla, a part of the adrenal gland, to release adrenaline and norepinephrine. These hormones are responsible for triggering the fight-or-flight response, which includes physiological changes like accelerated heart rate and increased respiration. The adrenal gland's secretion of these hormones is due to neural impulses from the sympathetic nervous system that are initially triggered by the hypothalamus in response to stress.