A vehicle placarded for hazardous materials must have placards on ___ sides.

Answer: C — 4

Hazard warnings must be visible from every direction. A vehicle carrying hazardous materials should display placards on all four sides—the front, rear, and both sides—so someone approaching from any angle can quickly identify the danger and take appropriate precautions. If placards were only on two or three sides, the warning might not be seen from the direction the vehicle is moving or approached from, defeating the purpose of rapid hazard communication. Therefore, placards on all four sides is the correct requirement.