What does the term "blind spot" refer to?

The term "blind spot" specifically refers to areas around a vehicle that are not visible through the mirrors. These spots can pose significant safety risks because drivers cannot see vehicles, pedestrians, or obstacles in those areas when checking their mirrors for traffic before changing lanes or making turns. It is crucial for drivers to be aware of their blind spots and to physically check over their shoulders to ensure it is safe to maneuver. Understanding this concept is vital for safe driving practices, as many accidents can occur from neglecting to check blind spots. The other options provided do not accurately describe what a blind spot is in the context of driving, focusing instead on different aspects related to road conditions or visibility.