Why are rear-end crashes common on highways?

Answer: B — Drivers follow too closely

Rear-end crashes are particularly common on highways primarily because drivers often follow too closely behind the vehicles in front of them. This practice, known as tailgating, reduces the driver's ability to react to sudden stops or changes in traffic conditions. On highways, traffic can vary quickly, and when a vehicle in front slows down or comes to a halt due to obstacles, brake lights, or traffic signals, a following driver may not have enough time or space to stop safely if they are too close. Maintaining a safe following distance allows drivers to have better visibility and reaction time, significantly reducing the likelihood of a collision. While the other options may contribute to dangerous driving behavior, they are not directly linked to the specific frequency of rear-end crashes as closely as following too closely is. For instance, not using turn signals, speeding, and frequently switching lanes can all lead to various incidents on the road, but they do not create the same immediate risk of a rear-end collision as inadequate following distance. Following too closely is a fundamental factor that can lead to a lack of stopping distance required to avoid a rear-end crash.