What does this sign with flashing lights indicate?

• Drivers must slow down and yield to the pedestrians crossing the road ahead.
  Explanation:

  "This sign alerts drivers to slow down and yield to pedestrians who are crossing the road when the light or signal is flashing."
• Drivers must slow down and yield to the truck entering the road from the right side.
• Drivers must come to a complete stop.
• None of the above.