Which of the following is true regarding blind spots when changing lanes?

The statement that vehicles should always be checked for blind spots before changing lanes is true because blind spots are areas around a vehicle that cannot be directly observed by the driver while looking in the mirrors or turning their head. These areas can hide other vehicles, pedestrians, or obstacles, which can lead to accidents if not accounted for during lane changes.

To ensure safety, it is crucial for drivers to actively check their blind spots by looking over their shoulder before initiating a lane change. This practice helps drivers to gain a comprehensive view of their surroundings and confirm that the lane is clear of any vehicles or objects that may not be visible through mirrors alone.

The other options suggest unsafe practices, such as remaining in others' blind spots or trusting other drivers to monitor their own blind spots, which can increase the risk of collisions. Thus, the emphasis on checking blind spots is vital for maintaining safety on the road.