The best way to ensure that you know when someone is in your blind spot is to
- check over your shoulder before you turn or change lanes ✓
- always be sure to use your mirrors
- scan 180 degrees
- ask your passenger to look for you
Answer: A. check over your shoulder before you turn or change lanes
The best way to know when someone is in your blind spot is to check over your shoulder before you turn or change lanes.
Why this is the answer
The handbook explains that mirrors, even when adjusted well, leave large areas you cannot see, and those side blind spots are the most dangerous. It says to do a shoulder check to be sure the blind spot on the side you plan to move toward is clear, turning your head at least 45 degrees that way. It also warns that blind spot detectors and cameras help but do not replace turning your head. That is why the shoulder check, not the mirrors alone, is what confirms a blind spot is clear before you turn or change lanes.
Why the other answers are wrong
- B. always be sure to use your mirrors — Mirrors are worth using, but the handbook says that even properly adjusted mirrors leave large areas you cannot see, so they cannot tell you the blind spot is clear.
- C. scan 180 degrees — Scanning 180 degrees is not the check the handbook describes; it asks for a quick look of at least 45 degrees over your shoulder in the direction you plan to move.
- D. ask your passenger to look for you — Nothing in the handbook assigns the blind spot check to a passenger, and the driver is the one who must confirm the space is clear before moving.
Remember it
Mirrors show what is behind and beside you; only a turned head shows what is hiding in the side blind spot.