What should a driver do before changing speed or switching lanes?

Answer: A — Look through the rear mirror to see vehicles behind

Before changing speed or switching lanes, a driver should always check the rear-view mirror to be aware of vehicles behind them. This action is crucial for ensuring safety on the road because it allows the driver to assess the distance and speed of any approaching vehicles from behind. Knowing what is happening behind the vehicle helps to avoid potential collisions when making maneuvers such as lane changes or speed adjustments. Additionally, checking the rear-view mirror serves as a preliminary step before making further checks, such as using side mirrors and checking blind spots. This practice enhances the driver's overall situational awareness, which is essential for making informed decisions while driving. It helps to confirm that there is enough space and that it is safe to proceed with the intended maneuver.