What is the "two-second rule"?

The "two-second rule" refers specifically to a method of determining a safe following distance between your vehicle and the vehicle ahead of you. By selecting a stationary object on the road, such as a sign or tree, you can gauge whether you are maintaining a safe distance. When the vehicle in front of you passes that object, you start counting "one thousand one, one thousand two." If you reach the same object before finishing the count, you are following too closely and should increase the distance. This rule helps ensure that you have ample time to react to any sudden stops or changes in traffic, fostering safer driving and reducing the risk of rear-end collisions.

While the other options address good driving practices, they do not pertain to the concept of following distance as effectively as the correct choice does. Merging onto highways and navigating intersections rely on different considerations, such as traffic flow and road conditions, and calculating stopping distances involves factors like speed and road conditions rather than a fixed time interval.