What does a white X-shaped crossbuck at a railroad crossing mean?

Answer: B — Yield to crossing trains

A white X-shaped crossbuck at a railroad crossing signifies that drivers should yield to crossing trains. This sign indicates that vehicles must give the right-of-way to any trains that may be traveling on the tracks. It serves as a warning that the tracks are nearby and that there could be an approaching train at any time. Drivers should slow down, check for any trains, and proceed only when it is safe to do so. While the other options present scenarios related to train crossings, they don't accurately capture the directive implied by the crossbuck sign. Understanding the meaning of this sign is crucial for ensuring safety at railroad crossings, where trains can appear suddenly and require full attention from drivers.