What term refers to signs, signals, markings, and devices that regulate, warn, or guide traffic?

The term that accurately refers to signs, signals, markings, and devices that regulate, warn, or guide traffic is "official traffic-control devices." This designation encompasses a broad range of visual aids used on roadways to manage vehicular and pedestrian traffic safely and efficiently. Official traffic-control devices include traffic lights, stop signs, yield signs, lane markings, highway signs, and various other indicators. These devices are standardized and recognized under traffic laws to ensure consistency and clarity for all road users, which is critical for maintaining public safety on the roads.

The other terms listed do not encompass the full scope of what is meant by official traffic-control devices. While "traffic signs" typically refer to a subset of these devices (specifically signs that convey specific messages), they do not include signals and markings. "Guiding signs" generally indicate directions or destinations, which is only one function of the broader category. "Regulatory markers" might refer to specific signs that enforce laws or regulations but again do not cover the entirety of devices used for traffic guidance and management. Therefore, the broad and comprehensive nature of the term "official traffic-control devices" is what makes it the correct choice.