For category A1, A2 or A practical instruction on the public road, what does Article 22 require of the instructor?

1. The instructor must ride a vehicle of that category or follow in a category B vehicle, and may teach at most 2 candidates at a time
2. The instructor must always ride pillion behind the candidate
3. The instructor may supervise any number of candidates from a fixed observation point
4. Motorcycle instruction on the public road is not permitted at all