What are the two types of warning devices for a railroad track?

The correct answer highlights the specific types of warning devices used at railroad crossings. The crossbuck sign is a traditional warning sign that indicates the presence of a railroad crossing, typically featuring the words "RAILROAD CROSSING." It serves to alert drivers and pedestrians to the potential of an oncoming train.

In addition to crossbucks, lights are also critical warning devices. These lights typically flash when a train is approaching, providing a clear visual indication for vehicles and pedestrians to stop and yield the right-of-way. The combination of crossbuck signs and flashing lights helps ensure safety by promoting awareness of nearby train activity.

While other options include plausible warning methods, they do not specifically represent the standard warning devices recognized for railroad crossings. For example, gates and bells are often associated with railroad crossings but are not universally required at all crossings, so they do not represent the two primary recognized types.