Which of the following describes the correct procedure for connecting the air lines to a trailer?

1. Connect the green electrical line first, then the red and blue air lines in any order.
2. The red emergency line should always be connected last.
3. Connect the blue service line, then the red emergency line, and finally the electrical line.
4. Connect the air lines (glad hands) by pressing them together and rotating them to a 90-degree angle to lock them in place.