Which flashing beacon must be turned on on the vehicle that closes the column if red and blue flashing beacons are turned on on the vehicle travelling at the front of the column?

• 1A blue flashing beacon.
• 2Blue and green flashing beacons.
• 3A green flashing beacon.
• 4Answers 2 and 3.
• 5Answers 1, 2, and 3.