What visual aids are used to recognize a passive railroad crossing?

Recognizing a passive railroad crossing is crucial for safety, as these locations do not have active warning devices like lights or gates to alert drivers of oncoming trains. The correct choice mentions that a passive railroad crossing is identified by several visual aids, including yellow circular advance warning signs, pavement markings, and crossbucks.

The yellow circular advance warning signs serve as a critical alert to drivers, indicating that they are approaching a railroad crossing. These signs typically feature a train symbol and a warning about the potential presence of trains. Pavement markings may also be present to further indicate the crossing and direct drivers' attention to the need for caution.

Crossbucks, which look like white signs with a black 'X' and the words "Railroad Crossing," are placed directly at the crossing to signify the location where trains may cross the road. They are a standard visual cue that indicates a crossing exists, but they do not provide any warnings of an approaching train.

The other options do not encompass the full range of visual aids present at a passive railroad crossing, making the correct choice the most comprehensive in terms of what drivers should look for in these situations.