Which lanes should stop for the school bus on a four-lane undivided highway?

• Both lanes which are going in the direction of the school bus.
• Both lanes which are going in the opposite direction of the school bus
• On a four-lane undivided highway, all four lanes must stop for a school bus.
  Explanation:

  "On a four-lane undivided highway, all four lanes must stop for a school bus."
• On a four-lane undivided highway, not a single lane needs to stop for the school bus.