Final answer:
The neurotransmitter that increases the heart rate in the fight-or-flight response is epinephrine (adrenaline).
Step-by-step explanation:
The neurotransmitter for the sympathetic division of the nervous system that increases the heart rate to prepare the body for the fight-or-flight response is c) Epinephrine (Adrenaline). The release of epinephrine and norepinephrine is stimulated by neural impulses from the sympathetic nervous system, particularly in response to stress. Both catecholamines work synergistically to increase heart rate, breathing rate, blood pressure, blood glucose, and muscle contractions. They also constrict blood vessels to non-essential organs and redirect blood flow during the fight-or-flight response.