How is a tractor (Zugmaschine) legally defined under KFG 1967 § 2 Abs. 1 Z 3?

1. A motor vehicle constructed exclusively for transporting heavy bulk goods on public highways
2. A self-propelled machine with permanently attached tools that cannot tow any trailers
3. Any four-wheeled passenger vehicle equipped with all-wheel drive
4. A motor vehicle constructed primarily to tow trailers, machinery, or tools, and only secondarily for carrying goods or persons