What does a circular blue sign containing a white diagonal arrow pointing down and to the right indicate (the mandatory 'Obavezno obilaženje s desne strane' sign)?

1. Mandatory passing of the island or obstacle on the right side (Obavezno obilaženje s desne strane)
2. One-way traffic to the right
3. Right turn prohibited at next junction
4. Motorcycles must exit the roadway immediately