A soldering gun is primarily used with which of the following materials?

A soldering gun is primarily used with metals, which is why choosing that option is the correct answer. The main function of a soldering gun is to heat a metal solder to its melting point, allowing it to flow and bond two metallic surfaces together. This process is essential in various applications, such as electronics, plumbing, and metalwork, where a strong electrical or mechanical connection is needed between two metal pieces.

Other materials like wood, plastic, and concrete are not typically used with a soldering gun. Wood and concrete would not benefit from soldering, as they require different methods for joining or treating. Plastic can be welded or glued but not soldered in the same way metals are. Thus, the specific association of soldering guns with metal makes it the correct choice.