Which of these is critical for ensuring train safety?

Regular checking of signals is crucial for ensuring train safety because signals are vital indications of track status, speed limits, and instructions for train operations. They provide real-time information to locomotive engineers, helping them to make informed decisions to safely navigate the tracks. By consistently monitoring these signals, engineers can react appropriately to varying conditions, such as the presence of other trains on the track, track obstructions, or changes in speed requirements. This practice helps prevent accidents and ensures the safe movement of trains within a network. In contrast, engaging in distractions such as reading novels, avoiding communication with the crew, and focusing solely on speed can lead to critical oversights that compromise safety.