The correct answer to this open question is the following.
As her professor distributed the mathematics test to the class, Blair's heart started to pound and her palms began to sweat. these physiological reactions were activated by her sympathetic nervous system.
Everybody has been in this kind of situation when you feel very nervous and anxious about what is about to happen. As part of the automatic nervous system, the sympathetic nervous system is the one in charge to start the response against a dangerous situation commonly known as "fight or flight response." That reaction is what keeps us alert of imminent risk or danger and allows us to recognize the situation and act.