What is a 'blind spot' (mrtvi ugao) on a commercial truck, and where are the largest blind zones located?

1. Areas around the vehicle that the driver cannot directly or indirectly see in mirrors: immediately in front of the high cab, directly behind the trailer, and along the entire right side of the truck
2. Areas located on the roof of the cab only
3. Zones visible only when the headlights are on high beam
4. Only the area under the spare tire