If an agricultural vehicle unavoidable soils a public asphalt road with wet clay or manure, what must the driver do under StVO § 92 until the road is cleaned?

1. Report the soiling to the road authority and carry on with the day's work
2. Switch on the hazard warning lights and leave the tractor parked on the verge
3. Spread sand over the mud and leave passing traffic to disperse it
4. Warn approaching traffic at once, using the appropriate danger warning signs for a slippery or soiled carriageway, and clean the roadway without delay