What is the correct safety sequence for connecting the air lines and electrical cable during the coupling process?

1. Connect the electrical cable first, turn on the lights, then connect the air lines
2. Connect the air lines (gladhands) first, verify the trailer brakes are secure, then connect the electrical cable
3. Connect all lines simultaneously while the tractor engine is running in reverse
4. Connect the lines in any order, as long as the blue line is connected before backing under the trailer