Final answer:
An elastic wrap is used after elevating an extremity to compress superficial vessels and force blood out, preventing blood pooling and swelling.
Step-by-step explanation:
When an extremity is elevated, the use of an elastic wrap serves to compress superficial vessels and force blood out of the extremity. This helps in preventing the accumulation of blood in the veins which could lead to swelling, a condition known as edema. It is effective because standing or remaining static for long periods causes blood pooling, especially in the legs. Elastic bandages or compression stockings apply sufficient pressure to help veins return blood to the heart, reducing the risk of fainting and swelling. Therefore, the correct answer to the question is D) Both A and C - Force blood out of the extremity and Compress superficial vessels.