What is the primary danger associated with heavy commercial vehicle 'Blind Spots' (Toter Winkel), particularly when turning right at urban intersections?

1. The driver cannot see the sky
2. Cyclists and pedestrians alongside the right passenger side may be completely invisible in standard fields of view, leading to fatal right-turn collisions (Abbiegeunfälle)
3. The engine consumes more fuel when mirrors are adjusted
4. Radio signals cannot penetrate the side glass