On a highway divided by a median, which vehicles must stop for a school bus with flashing red lights?

• Only vehicles behind the school bus.
  Explanation:

  "On a highway divided by a median, only vehicles traveling in the same direction as the school bus (those behind it) must stop when the bus has its red lights flashing and stop sign extended. Vehicles on the opposite side of the median are not required to stop, as the median acts as a safety barrier."
• Vehicles in all lanes, both directions.
• Only vehicles in front of the school bus.
• No vehicle need to stop.