What is the meaning of a flashing yellow (feu jaune clignotant) traffic light at an intersection?

1. Proceed with caution, respecting priority signs or applying the default priority-to-the-right rule if no signs are present
2. The road is closed to all traffic and all vehicles must turn back
3. Drivers on all approaches must come to a mandatory 3-second stop before proceeding
4. Only public transport buses and emergency vehicles may enter the intersection