_______ accelerates heart by stimulating adrenal medulla through the sympathetic nerves.
The correct option is B Adrenaline
Sympathetic nervous system is a part of autonomous nervous system and releases adrenaline. Adrenaline, also known as epinephrine, is secreted from adrenal medulla in response to stress conditions in the body. Whenever homeostasis of body is disturbed, adrenaline is released which increase alertness, piloerection, increase in heart beat and strength of heart contraction. These reactions are considered as fight or flight reactions induced by adrenaline.