What types of devices can mark a railroad crossing?

The correct response highlights the various devices that are employed to indicate a railroad crossing to drivers. Warning signs, such as the classic "Railroad Crossing" sign, are specifically designed to alert vehicles that they are approaching tracks and may need to stop or proceed with caution. Pavement markings, often used in conjunction with these signs, help to guide vehicles safely across the tracks.

Crossbucks are the standard sign found at most train crossings; they specifically denote the presence of a railroad track. Signal lights are also crucial since they provide visual alerts when a train is approaching, often flashing to indicate that vehicles should stop and not proceed onto the tracks.

Each of these elements works together to enhance safety at railroad crossings, making it evident that multiple forms of signaling are vital in warning drivers of the potential dangers presented by oncoming trains. In contrast, the other options each focus on either a singular type of signaling device or are not specific to railroad crossings, which underscores why they are not appropriate choices in this context.