The correct option is A Adrenaline
Emergency hormone in animals is adrenaline. This hormone is secreted by adrenal gland and also called as 'hormones of Fight or Flight'. It prepares the body to face emergency conditions of physical stress like danger, anger, excitement; etc. It is secreted in small amounts all the time but in large amounts when a person is frightened. The target organ is heart so heart beat increases, resulting in supply of more oxygen in our muscles. It allows more supply of glucose into the blood to give us a lot of energy quickly to fight or flight from the frightening situation.