What does a circular white sign with a red border containing '10 t' between two horizontal arrows pointing toward a single wheel axle indicate (Znak II-25, 'ograničenje osovinskog opterećenja')?

1. Prohibition of vehicles whose actual single-axle load exceeds 10 tonnes (Zabrana saobraćaja za vozila koja prekoračuju određeno osovinsko opterećenje)
2. Prohibition of vehicles whose gross combination weight exceeds 10 tonnes
3. Mandatory 10 tonnes of cargo in the truck bed
4. Maximum speed limit of 10 km/h for trucks