Which of the following items can serve as an effective tourniquet?

A commercially available tourniquet is specifically designed for controlling severe bleeding and is constructed to be highly effective and safe for that purpose. These tourniquets often have features such as a tightening mechanism and are made from materials that can withstand the pressure needed to occlude blood flow. They can be quickly and securely applied, which is critical in emergency situations. Their design takes into account the need to apply significant pressure without causing unnecessary injury to the tissue underneath, making them the most reliable choice for managing life-threatening hemorrhages.

Each of the other options, while useful for different medical purposes, do not provide the same level of efficacy or safety when used as a tourniquet. An elastic bandage, padded gauze, or surgical tape may assist in bandaging or securing dressings, but they lack the necessary design and functionality to effectively control severe bleeding in the way a purpose-built tourniquet would.