What is essential to check on a bus before departure regarding safety devices?

It's crucial to ensure that all safety devices on a bus are in proper working order before departure to guarantee the safety of passengers and the driver. Checking that fire extinguishers are full ensures that fire emergencies can be effectively managed, while a stocked first aid kit is vital for addressing any medical issues that arise during transport. Furthermore, confirming that all signaling devices are functioning properly is necessary for safe communication with other road users and to alert them of any necessary maneuvers or emergencies. Therefore, the correct answer emphasizes the importance of a thorough check of all these critical safety devices, ensuring that the bus is fully equipped to handle potential emergencies. This comprehensive safety check is essential to maintain the well-being of everyone on board and adhere to safety regulations.