When is it obligatory to operate a flashing yellow lamp above the driver’s compartment of a truck?

1. Correct answer: When the freight’s width is more than 3 meters.
2. When the freight’s width is three meters or less.
3. When carrying disposable equipment.
4. When the freight’s width is more than 2.80 meters.

WhyA flashing yellow lamp above the cab is also required when the freight is wider than 3 meters.