What safety equipment is required in every vehicle in Idaho?

The correct answer highlights essential safety equipment that is mandated for vehicles in Idaho. A working horn is a fundamental requirement that ensures the driver can alert others of their presence, especially in emergencies or when warning pedestrians. Seat belts are crucial for passenger safety, significantly reducing the risk of injury or death in the event of a crash. The inclusion of a spare tire reflects preparedness for common roadside emergencies, ensuring that drivers can address flat tires and maintain mobility.

This combination of equipment promotes overall safety on the roads, aligning with both legal requirements and best practices for responsible driving. The other options include useful items, but they do not encompass the full range of mandatory safety equipment recognized in Idaho.