The correct answer is A. Epinephrine
Step-by-step explanation:
The "fight or flight response" is a physiological response that occurs due to a threat or attack and implies animals facing or avoiding the thread. This response involves the nervous system and also the adrenal medulla that produces the epinephrine or adrenaline which is one of the main hormones in the "fight or flight response" and causes muscular tension, rapid heartbeat, and dilatation of the pupil, which is part of the reactions in this response. Therefore, the hormone that is called adrenaline and that is one fo the main substances that cause the "fight and flight response" is the epinephrine.