What does a circular white sign with a red border containing the symbol of a drawbar cargo trailer behind a car indicate ('zabrana saobraćaja za vozila koja vuku priključno vozilo')?

1. Prohibition of traffic for motor vehicles towing a trailer other than a light trailer or single-axle caravan (Zabrana saobraćaja za motorna vozila koja vuku priključno vozilo)
2. Mandatory trailer towing route
3. Caravan camping resort nearby
4. Prohibition of passenger cars only