Buses may carry 500 pounds of total allowed hazardous materials, and no more than ___ pounds of any one class.

The correct answer indicates that buses can carry a maximum of 100 pounds of hazardous materials from any single class. This regulation is in place to ensure safety on public transportation systems by limiting the potential risk associated with transporting hazardous materials.

The intent behind this limitation is to minimize the danger of a significant incident that could arise from transporting large quantities of a single class of hazardous material, which could result in severe consequences in the event of a spill or accident. By restricting the amount to 100 pounds for any one class, it encourages a diversified approach to the types of materials that can be transported, thereby reducing the risk associated with mishaps.

This regulation is important for maintaining safety standards while still allowing for the transportation of necessary materials. In this context, while it might be permissible to transport 500 pounds of hazardous materials in total, doing so in a more controlled manner with respect to the classes of those materials is essential.