A pipe wrench is primarily used for which of the following tasks?

The primary function of a pipe wrench is to grip rounded surfaces, particularly in plumbing applications. Pipe wrenches are designed with serrated jaws that are effective at clamping down on cylindrical objects, like pipes. This gripping action allows the technician to turn or loosen pipes and fittings, which are often rounded. The design of the wrench accommodates the unique challenges presented by plumbing work, where most of the components are circular.

While measuring the volume of liquid and applying specific torque relate to other tools and tasks, they are not the main functions of a pipe wrench. Similarly, gripping flat surfaces of nuts and bolts is more suited to other types of wrenches specifically designed for that purpose. Therefore, the correct choice emphasizes the pipe wrench's specialized role in gripping rounded surfaces, making it an essential tool for plumbing tasks.