When instructed to reduce speed for fuel conservation, what throttle positions does the speed reduction apply to?

The correct answer highlights the throttle positions where speed reduction for fuel conservation is applicable, specifically from position 3 through 8. This range of throttle positions is considered optimal for achieving fuel savings while maintaining sufficient power to handle the train effectively.

Throttle positions 1 and 2 are generally used for starting and low-speed operations, where fuel efficiency might not be the primary focus, as the train requires more power to achieve motion. Positions 4 through 6, while they might also be seen as moderate power levels, do not encompass the full range needed for effective speed reduction as per the fuel conservation guidelines.

By focusing on throttle positions 3 through 8, train crews can maximize fuel efficiency without significantly sacrificing control and performance on grades and when accelerating. This understanding is crucial for effectively managing the locomotive's power while on the move.