Final answer:
A driver knows it is safe to return to their lane after passing when they can see the vehicle they passed in the rearview mirror, ensuring a safe distance.
Step-by-step explanation:
A driver knows it is clear to return to the driving lane after passing another car when they can see the vehicle they have passed in their rearview mirror, indicating they have left enough room between the vehicles to change lanes safely.
When on the road, it's crucial to maintain a safe distance from other vehicles to prevent accidents.
After completing a passing maneuver, the driver should ensure that they can see the front bumper of the car they passed in the rearview mirror before moving back into the driving lane to ensure there is sufficient space. This practice is part of defensive driving and is taught as a safety measure in driver's education courses and is essential for maintaining safety on the road.