Which tool is designed for turning and holding metal pipes?

The tool designed specifically for turning and holding metal pipes is a pipe wrench. This tool features serrated jaws that provide a strong grip on pipes, allowing for the application of torque necessary to loosen or tighten them. The design of the pipe wrench, which includes a long handle for leverage and an adjustable jaw to fit different pipe sizes, makes it essential for plumbing and mechanical tasks involving metal piping.

In contrast, the other choices serve different purposes. A pipe plug is used to seal the end of a pipe, preventing flow through that section. A pipe tee is a fitting that allows for the connection of three pipes at a junction, facilitating the branching of a pipeline. A pipe reducer serves to connect two pipes of different diameters, allowing for a transition in pipe size. None of these tools are designed to grip and turn pipes as effectively as a pipe wrench, reinforcing the significance of the correct answer in the context of metal pipe handling.