Which safety equipment must be present on a school bus?

The presence of seat belts, stop signal arms, and emergency exits is essential for ensuring the safety of students when riding a school bus. Seat belts help secure passengers, reducing the risk of injury during sudden stops or accidents. Stop signal arms are critical for protecting children as they board and disembark from the bus, signaling to other drivers that they must stop. Emergency exits are vital for the safe evacuation of passengers in case of an emergency, providing additional escape routes beyond the main door. Each of these safety features plays a significant role in safeguarding the well-being of students, making their inclusion on school buses a requirement.

While other safety equipment like fire extinguishers and first aid kits is important, the specific components mentioned in this correct option are directly tied to the day-to-day operational safety of students during their transit to and from school.