What is one of the primary causes of vehicle rollovers?

Answer: B — Improper load securement

Improper load securement is one of the primary causes of vehicle rollovers because it can significantly affect the vehicle's center of gravity and balance. When cargo is not secured properly, it can shift during transit, especially during turns, stops, or rapid acceleration. This shifting can lead to an unstable load, increasing the likelihood of tipping over. The center of gravity of a vehicle plays a crucial role in its stability; when the load is unevenly distributed or shifts, it may exceed the vehicle's stability threshold, resulting in a rollover. In contrast, while excessive braking, adverse weather conditions, and ignoring traffic signals can contribute to accidents, they generally do not directly cause rollovers in the same way that improper load securement does. Properly secured loads maintain vehicle stability, reducing the risk of rollovers.