What type of train is classified as a freight train?

A freight train is classified as any train that does not carry passengers; it is specifically built and designed to transport goods and materials. This classification emphasizes the primary function of the train, distinguishing it from passenger trains, which are intended to carry individuals from one location to another.

The other choices focus on narrower definitions that do not encompass the broader category of freight trains. For instance, limiting freight trains to those that only carry dangerous goods excludes many other types of cargo, such as bulk commodities, intermodal containers, and general merchandise. Similarly, commuter trains are specifically designed to transport passengers, even if they stop at limited locations, while scheduled train services between cities generally refer to passenger trains rather than freight. Thus, the correct choice highlights the inclusive nature of freight train classification.