Which statement is correct about uncoupling shut-off valves for New Jersey CDL doubles/triples operation?

1. Close air shut-offs at the rear of the first semitrailer and on the dolly if equipped
2. Uncouple on a grade whenever possible for item 81-1
3. Leave disconnected lines dragging for item 81-2
4. Release the pintle hook before support is set for item 81-3