Final answer:
Norepinephrine is secreted by the adrenal medulla and it prepares the body for the fight-or-flight response by targeting tissues that increase heart rate, blood flow, and energy availability.
Step-by-step explanation:
Norepinephrine is a hormone and neurotransmitter secreted by the adrenal medulla, which is the correct answer to the question, making option C (Adrenal medulla) the correct answer. The primary role of norepinephrine is to prepare the body for the fight-or-flight response during stressful situations. This hormone is part of a group of hormones called catecholamines, which also includes epinephrine (adrenaline). When released into the bloodstream, norepinephrine targets various tissues in the body, inducing physiological changes such as increasing heart rate, dilating the bronchi in the lungs, increasing blood flow to muscles, and elevating blood sugar levels for quick energy use. These effects help an organism respond to threats effectively.