What is the required action when passing a solid yellow aspect?

Answer: B — Proceed at restricted speed

In railroad signaling, a solid yellow aspect indicates that a train must proceed, but with caution. The correct action requires a reduction in speed, allowing the train to be prepared for a potential stop at the next signal, which could indicate the need to halt due to hazards or upcoming track conditions. This is essential for maintaining safety, as operators must be aware of and ready to respond to upcoming signal changes. While other options detail speed reductions or stopping requirements, the key aspect of the correct answer is that it emphasizes proceeding at restricted speed. This means the train must move cautiously, watching for any obstructions or signals ahead, and being ready to stop. Understanding this concept is crucial for safe train operation, especially when faced with varying circumstances that may arise on the tracks.