Final answer:
Dangerous goods transported on Ontario roads and highways are identified by a diamond-shaped placard. This identification is part of the NFPA 704 Hazard Identification System, which uses a color-coded diamond symbol to communicate various substance hazards.
Step-by-step explanation:
Dangerous goods transported on Ontario roads and highways are identified by: Dangerous goods, which can include chemicals and substances that pose various types of hazards, need clear identification for transport safety. In Ontario, these goods are marked with A) A diamond-shaped placard. This placarding is in line with the National Fire Protection Agency (NFPA) 704 Hazard Identification System, which is designed to provide crucial safety information about substances. The NFPA 704 system uses a diamond-shaped symbol with different colored sections to specify various hazards, including fire, health, reactivity, and special hazards. Hazard ratings are provided within each section of the diamond on a scale from 0 (no hazard) to 4 (extremely hazardous). The red diamond indicates fire hazard levels, the blue diamond is for health hazards, yellow signifies reactivity, and white designates special hazards such as oxidizers or water-reactive substances.