Is it allowed for priority vehicles on emergency service to use only the light signal?
A)No, they must simultaneously use the light and acoustic signal
B)Only on urban roads; on interurban roads they must always use the acoustic signal
C)Yes, when it does not pose a danger to other users.Correct
# Explanation
Priority vehicles on emergency service may use only the light signal (blue light) when this is sufficient to warn other drivers without creating dangerous situations. However, the safest and most recommended practice is to combine the light signal with the acoustic signal (siren) to ensure that everyone perceives the approach of the emergency vehicle. The rule allows flexibility as long as road safety is prioritized.