What is the purpose of the 'Anti-Jackknife Articulation Controller' (Knickwinkelsteuerung / Anti-Knick-System) in a rear-engine pusher articulated bus (Schubgelenkbus)?

1. It locks the articulation joint permanently into a straight line
2. It monitors the articulation angle between the front and rear sections; if the rear pusher trailer begins to push the front section sideways into a jackknife skid, it automatically dampens articulation hydraulics and throttles engine power
3. It allows the rear section to steer completely independently without a driver
4. It detaches the rear section automatically at 60 km/h