Increased trade across national boarders
Stress signals are the ways you express stress for example: ruminating thoughts, shaking of legs, pacing.
Stressors are things that stress you, for example relationship problems or exam.
while you have to answer this question for yourself, I can give you some examples:
shaking before an exam
ruminating thoughts before meeting parents
pacing before a flight
A . 12 states make up the Midwest