You want to move from lane 2 to lane 3 on a road with three lanes in each direction. What is the best way to avoid missing a vehicle in your blind spot?

1. ①Check only the interior rear-view mirror and change lanes right away
2. ②Once the turn signal is on, the car behind will move out of the way, so no further check is needed
3. ③Turn on the turn signal, check the right side mirror, then turn your head to check the blind spot directly before changing lanes
4. ④If no car appears in the side mirror, there is none in the blind spot either, so change lanes quickly