Final answer:
A placard vehicle must have at least one placard. Placards are required for vehicles carrying certain quantities of hazardous materials and provide important information to emergency responders.
Step-by-step explanation:
A placard vehicle must have at least one placard.
Placards are used to display information about hazardous materials being transported. They provide important information to emergency responders in the event of an accident or spill.
In the United States, placards are required on vehicles carrying certain quantities of hazardous materials, as specified by the Department of Transportation (DOT). These placards help identify the specific type of hazardous material being transported, such as flammable liquids, corrosive substances, or poisonous gases.