What characteristic describes the plug of a plug valve?

The characteristic that describes the plug of a plug valve is that it is shaped like a cone. This conical design allows the plug to rotate within the valve body, effectively controlling the flow of fluid through the valve. The cone shape enables a tighter seal when the valve is closed, as it can fit snugly against the seat of the valve, minimizing leakage.

Additionally, the conical shape provides a clear pathway for flow when the valve is opened, as the plug can be turned to allow fluid to pass through the larger opening. This design is particularly advantageous for applications requiring quick and reliable shut-off capabilities.

Other options present characteristics that do not align with the functional design of a plug valve, making the conical shape the correct choice for accurately depicting the structure and operation of the valve.