Final answer:
The first stage of the General Adaptation Syndrome (GAS) is the alarm reaction, which is the immediate response to stress characterized by fight-or-flight physiological reactions.
Step-by-step explanation:
The first stage of the General Adaptation Syndrome (GAS) is known as the alarm reaction. This stage is characterized by the body's immediate physiological reaction to a stressor, which is analogous to the fight-or-flight response. The body alarms the individual with a cascade of physiological reactions mediated by hormones such as epinephrine and norepinephrine, providing the energy needed to deal with the situation. Hans Selye, an early researcher in the field of stress, identified this process as the body's nonspecific physiological response to stress.
Alarm reaction is the correct answer to the student's question, marking it as option A. This phase is designed as a short-term response, and once the stressor is relieved, the body typically returns to normal functioning.