How long should the flag attached to the extension or load of a vehicle be if the load extends more than 1.5 meters?

• 20 centimeters
• 25 centimeters
• 30 centimeters
  Explanation:

  "If a vehicle’s load extends more than 1.5 meters beyond the rear, a red flag must be attached to the end of the load during daylight hours. The flag must be at least 30 centimeters (one foot) long on each side of the square to ensure it is clearly visible to other drivers."
• 35 centimeters