Which fittings are used to join pipes made from different materials?

The choice of adapters is correct because they are specifically designed to join pipes made from different materials or with differing diameters. Adapters come in various forms, such as threaded or soldered connections, allowing for flexibility in joining systems that have incompatible ends. This feature is crucial when working with diverse plumbing materials like PVC, copper, or PEX, as each type requires appropriate transitions that adapters provide.

In contrast, couplings are primarily used for connecting two pieces of the same type and size of pipe, making them unsuitable for differing materials. Reducers are tailored for transitioning between different diameters within similar materials rather than addressing material compatibility. Wyes allow for branching connections between pipes, but they do not serve the purpose of joining pipes of different materials, emphasizing the unique role of adapters in cross-material connections.