What is an important safety feature that should be used when children are boarding the bus?

Answer: D — Flashing red lights

Flashing red lights are essential safety features that indicate when a school bus is picking up or dropping off children. When these lights are activated, it signals to other drivers that they must stop and not proceed past the bus to ensure that children can safely board or exit the vehicle. This visual cue is critical for maintaining a safe environment around the bus, as it helps prevent accidents during the vulnerable moments when children are entering or leaving the bus. Proper use of flashing red lights creates a clear expectation for all road users, significantly reducing the risk of incidents in the vicinity of school buses.