An anatomy and physiology instructor scratches chalk across the blackboard causing a screeching sound. Several students get a feeling like their "hair is standing on end." This response is part of the sympathetic stress reaction and is called what?

Pilorection

Explanation:

The sympathetic nervous system directs the body's rapid involuntary response to dangerous or stressful situations

The feeling of "hair is standing on end" gives goosebumps or technically we one can say pilorection

Pilorection is defined as erection of the hair of skin due to contraction of the tiny arrectores pilorum muscles that elevate the hair follicles above the rest of the skin and move the hair vertically, so the hair seems to stand on end