What should you maintain until the next signal is visible after returning to the main track?

Answer: C — Restricted speed

Maintaining restricted speed after returning to the main track is essential for ensuring safety until the next signal is visible. Restricted speed allows a train to operate at a speed that can be stopped within half the range of vision, which is crucial in preventing collisions or accidents, especially in scenarios where visibility may be limited due to the terrain, weather conditions, or other factors. This approach also allows the conductor to react appropriately to any unexpected situations or obstacles on the track that may not be visible until they approach closely. By adhering to restricted speed, a conductor ensures that they can have adequate time to react to signals or other trains, maintaining overall operational safety on the rail network.