What is the purpose of a 'dilemma zone' and how do advance detectors address it?

1. The dilemma zone is a cabinet wiring challenge; advance detectors have no role
2. The dilemma zone is the area where a driver can neither stop safely nor clear the intersection before the red; advance detectors extend green to prevent vehicles from being in this zone at yellow onset
3. The dilemma zone is the area between two coordinated signals; advance detectors count vehicles
4. The dilemma zone is the conflict zone in the middle of the intersection; advance detectors monitor for conflicts