Final answer:
The constriction of blood vessels in the skin when exposed to cold is an example of a negative feedback loop, which aids in body temperature regulation and maintaining homeostasis.
Step-by-step explanation:
When stepping from a warm room to the cold winter air of South Dakota, the constriction of blood vessels in the skin is an example of a negative feedback loop. This physiological response helps to retain heat in the core of the body by reducing the amount of blood flow to the extremities and the surface of the skin, which can lose heat to the environment. Therefore, the answer is (b) negative feedback loop.
The process involves several components: a stimulus (the cold), a sensor that detects this stimulus, a control center that processes the information, and effectors (the blood vessels) that respond to counteract the change - this restores the body to the desired state of body temperature regulation and maintains homeostasis.