What should you verify about the air and electrical lines when coupling each additional trailer in a doubles or triples combination?

Pick an answer

1. Only the electrical lines matter; air lines can be skipped on the rear trailers entirely with no effect on how the brakes work
2. Air and electrical lines are unnecessary for any trailer behind the first
3. That each trailer's lines are properly connected so brakes and lights work all the way to the last unit
4. Only the lead trailer's lines need to be connected; the others are optional

Correct!

Not quite. The correct answer is highlighted.