How does a school bus's design enhance its overall safety during a rollover?

Answer: C — By having a rollover tested structure

The design of a school bus incorporates specific engineering features that are rigorously tested to enhance safety, particularly concerning rollover incidents. A rollover-tested structure is designed to withstand the forces experienced during a rollover, helping to protect the occupants inside. These structures are reinforced to maintain their integrity even when subjected to significant lateral forces, which helps prevent the roof from collapsing onto the passengers. This testing process involves evaluating the bus under controlled conditions to simulate rolling scenarios, ensuring that safety measures are effective. Moreover, rollover-tested structures are a vital part of the overall safety strategy that schools employ, contributing to a safe environment for students traveling on buses. In contrast, smaller windows and collapsible structures do not directly enhance the safety during rollover situations, as they do not optimize the overall integrity of the bus's frame. Minimizing seatbelt usage would not contribute to safety, as seatbelts are crucial for securing passengers and preventing injuries in any accident type. Therefore, the focus on rollover-tested structures stands out as the key feature that enhances a school bus's safety during such events.