What must be displayed on magazine doors to indicate hazards?

The correct response focuses on the necessity of displaying fire symbols on magazine doors to effectively indicate hazards. These symbols serve as a universal language to communicate specific risks associated with munitions storage, such as explosive materials. Their purpose is to ensure that personnel can quickly recognize potential dangers when approaching the magazine.

Fire symbols are crucial for providing clear and immediate visual cues to emergency responders and trained personnel. They help in conveying vital information, such as whether the materials stored are flammable or explosive, and indicate the necessary precautions and responses in case of an emergency. This awareness is essential for promoting safety and preventing accidents in environments that handle hazardous materials. In contrast, options like identification numbers, manufacturer labels, and access codes do not offer this critical immediate recognition of hazards.