A triangular orange sign on the rear of a vehicle indicates what?

Answer: D — Vehicle cannot travel faster than 25 mph

The correct answer is D. A triangular orange sign on the rear of a vehicle indicates that the vehicle cannot travel faster than 25 mph. This sign is called a slow-moving vehicle sign and is typically displayed on vehicles that cannot travel at speeds greater than 25 mph, such as farm equipment or construction vehicles. This sign alerts other drivers to be aware that the vehicle in front of them is moving at a slower speed than normal traffic and to adjust their driving accordingly to ensure safety on the road. In this case, options A, B, and C are incorrect because the triangular orange sign specifically indicates that the vehicle cannot travel faster than 25 mph, rather than carrying hazardous materials, moving slowly, or being an emergency vehicle.