Next, pull the middle line. This feeds the trunk lock and gas door lock. Note that these lines might have been swapped at some point in the car's history - after pumping a vacuum on it, check to see whether the trunk and gas door are locked. If not, this might be feeding the rear passenger door lock actuator instead.
If you find a leak on this line, and it is indeed serving the trunk lock and gas door lock actuators, you will need to continue your diagnosis by testing the trunk actuator and gas door lock actuators separately. That is covered in step 17.