How does the design of a bus help protect against rollovers?

The design of a bus that helps protect against rollovers primarily focuses on creating a low center of gravity and a wide wheelbase. A low center of gravity lowers the bus's center of mass, making it less prone to tipping over during sharp turns or sudden maneuvers. This stability is crucial, especially for a vehicle that carries many passengers and has a tall profile compared to other vehicles.

Additionally, a wide wheelbase increases the vehicle's stability by providing a broader stance that helps distribute weight more evenly and prevents the bus from tilting excessively. Together, these design features work effectively to reduce the risk of rollovers, making buses safer for passengers and drivers. The other options do not provide the same level of protection against rollovers, as increasing body height can actually raise the center of gravity, and using lightweight materials could compromise structural integrity without addressing stability. Limiting the number of passengers does not inherently contribute to the structural design aimed at rollover prevention.