During the tractor protection valve check, the control line glad hand is disconnected and a full brake application is made. What should happen?

1. Tractor brakes function normally, trailer service brakes do not function, and air loss stops when protection closes
2. Trailer service brakes function normally because the control line is disconnected
3. No air should ever escape after the brake application begins
4. The trailer supply valve should stay open until tractor pressure reaches zero