A vehicle placarded for hazardous materials must have placards on how many sides?

Answer: C — 4 sides

A vehicle that is placarded for hazardous materials is required to display placards on all four sides. This is to ensure that anyone in the vicinity of the vehicle, including emergency responders, is immediately aware of the presence of hazardous materials, regardless of the direction from which the vehicle is approached. By having placards on each side, it enhances visibility and communication about the materials being transported, thereby increasing safety. The four-sided requirement is a standard regulation to ensure comprehensive identification and awareness for those around the vehicle, including onlookers, first responders, and others who may be involved in an emergency situation.