Which physical change occurs when the body enters alarm mode due to stress?

• A. Pupils in the eyes dilating to improve vision
• B. Hair standing on end
• C. Skin flushing red
• D. Hands trembling

Answer: (A)

When the body moves into alarm mode, the sympathetic nervous system kicks in as part of the fight-or-flight response. This causes the pupils to dilate, widening the opening in the eye to let in more light and improve our ability to detect movement and react quickly. The dilation is a classic, reliable sign of this stress response because it directly enhances vision under threat by increasing light intake and focus.

Hair standing on end can happen with fear or cold but isn’t a primary, consistent reaction of the alarm state. Skin flushing is not typical of the alarm response; stress often makes the skin paler or sweaty rather than flushed. Hands trembling can occur from adrenaline, but it’s less specific to the alarm mode than pupil dilation.