What must be in working condition for the vehicle's signaling system?

The requirement for a vehicle's signaling system to be in working condition includes the proper functioning of both turn signals and hazard lights. Turn signals are essential for communicating directional intentions to other drivers, which is crucial for safe driving and adherence to road laws. Effective signaling helps prevent accidents by allowing other road users to anticipate a vehicle's movements.

Hazard lights serve a different purpose, alerting other drivers to the presence of a stationary or slow-moving vehicle, often in an emergency situation. Having both turn signals and hazard lights operational ensures that drivers can signal their movements and warn others appropriately, contributing to overall road safety.

The other options indicate a limited or inadequate understanding of signaling requirements, such as only requiring brake lights or just one type of signal. This emphasizes the importance of having the complete signaling system function properly for effective communication on the road.