If an identification sign is installed on the vehicle "Road Train," in which of the listed cases must it be turned on?

• 1It must be turned on at all times while travelling.
• 2It must be turned on during a forced stop, stopping, or parking on the road during the hours of darkness.
• 3It must be turned on during a forced stop, stopping, or parking on the road in conditions of reduced visibility.
• 4Answers 2 and 3.
• 5Answers 1, 2, and 3.