What is the role of emergency lights on a train?

Emergency lights on a train are crucial for ensuring visibility during an incident. When an emergency occurs, these lights serve to illuminate the area, making it easier for first responders to locate the scene and assess the situation quickly. Additionally, they enhance the visibility of the train itself, helping to prevent further accidents or collisions by signaling to other trains and vehicles that something is amiss. This functionality is vital in ensuring safety and facilitating a rapid response in emergencies, which is why this choice correctly identifies the primary role of emergency lights on a train.

The other options suggest functions that, while important in their own contexts, do not fully capture the specific purpose of emergency lights. For instance, navigation for the crew is typically aided by other systems, and distress signals may be communicated through different means. Indicating normal operations is not aligned with the purpose of emergency lights, which are intended for situations that deviate from standard operation.