Which stake has two cylindrical horns of different diameters and is used for forming, seaming, and riveting?

The correct choice describes a tool that is specifically designed for various metalworking tasks, particularly in sheet metal fabrication. When identifying a stake with two cylindrical horns of different diameters, one recognizes that such a tool is generally used for shaping, bending, and manipulating metal with precision.

The term "conductor," which was chosen, typically refers to a material or device that allows the flow of electric current. This does not relate to metalworking or forming processes in sheet metal.

Instead, the tool that features the two cylindrical horns would more commonly be referred to as a "hollow mandrel" or "solid mandrel," which are types specifically used for forming and shaping materials. However, a hollow mandrel, which allows for the manipulation and seaming of materials, is distinct in its ability to accommodate variations in metal thickness and diameter.

In summary, the correct answer is linked to the design and functionality of tools used for shaping and manipulating metal, where the cylindrical horns allow artisans to create curves, seams, and rivets efficiently. Understanding the specific characteristics of these tools aids in selecting the proper equipment for various HVAC and sheet metal tasks.