When a semitrailer is parked on the shoulder of a divided highway and two flags are being used in the place of lighted lamps, the final flag should be placed ____ behind the vehicle.

If lighted lamps are not required to be used during an emergency stop, they should be replaced by two red flags. When a semitrailer is parked on the shoulder of a divided highway and two flags are being used in the place of lighted lamps, the final flag should be placed 200 feet behind the vehicle.