Which of the following is not part of the fight-or-flight response?

REDUCTION OF MENTAL ACTIVITY is not part of the fight or flight response.
Fight or flight response is stimulated in humans when one is confronted with danger or stress. During this period, the adrenal gland releases epinephrine hormone into the blood stream, this causes, dilation of the blood vessel and leads to increased heart rate, increased respiratory rate, suppression of the immune and digestive system an the dilation of the pupils.

This is true. yes. indeed.