Final answer:
When cold is applied to an area, blood vessels in the skin contract or constrict (vasoconstriction) to reduce blood flow close to the surface of the body.
Step-by-step explanation:
When cold is applied to an area, the blood vessels in the skin contract or constrict (vasoconstriction), which reduces blood flow close to the surface of the body. This helps to minimize heat loss and maintain body temperature.