What does a circular white sign with a red border containing the graphic of an automobile and a motorcycle indicate (Znak II-21, 'Zabrana saobraćaja za motorna vozila')?

1. Prohibition of traffic for all motor vehicles except single-track mopeds without sidecars (Zabrana saobraćaja za motorna vozila)
2. Shared fast lane for cars and motorcycles only
3. Overtaking permitted between cars and motorcycles
4. Free public parking for cars and motorcycles