Placards of cylinders identify the content.

Placards of cylinders identify the content.

• A. Caps
• B. Serial Numbers
• C. Labels
• D. Placards

Answer: (D)

Placards serve as the external hazard communication for transported materials. They summarize the content and hazard class, so anyone handling a cylinder or responding to an incident can quickly assess what’s inside and what precautions to take. This is why placards are the correct choice: they identify the material by signaling the content and associated hazards on the outside of the container. Caps do not convey content, they just cover the valve; serial numbers identify a specific item but not its contents; labels on a cylinder indicate the material, but placards provide the standardized, outer sign used to identify content across carriers and locations.

Placards serve as the external hazard communication for transported materials. They summarize the content and hazard class, so anyone handling a cylinder or responding to an incident can quickly assess what’s inside and what precautions to take. This is why placards are the correct choice: they identify the material by signaling the content and associated hazards on the outside of the container. Caps do not convey content, they just cover the valve; serial numbers identify a specific item but not its contents; labels on a cylinder indicate the material, but placards provide the standardized, outer sign used to identify content across carriers and locations.