Where must Product ID numbers appear on a portable tank containing hazardous materials?

Answer: B — On each side and both ends

The requirement for Product ID numbers to appear on each side and both ends of a portable tank containing hazardous materials ensures that the information is clearly visible from multiple angles. This is crucial for safety, as it allows emergency responders, shipping personnel, and other individuals to quickly identify the contents of the tank in the event of an incident or spill. Having this information displayed in multiple locations helps to improve situational awareness and reduces the risk of mishandling the materials. It facilitates effective emergency response by providing immediate access to important details, such as the nature of the hazardous material being transported, which is essential for implementing the correct safety protocols and precautions. This requirement is part of the regulations that govern the transportation of hazardous materials, reflecting the serious nature of handling such substances and the need for clear identification to protect public health and safety.