What does this road sign indicate to drivers regarding the area ahead?

• The road is closed to all traffic during school hours.
• There is a school zone ahead, and drivers should drive with caution and look out for children.
  Explanation:

  "This sign shows that there is a school zone ahead. Drive with caution and look out for children."
• Only school buses are allowed in the area ahead.
• The speed limit is reduced to 15 mph only when school is in session.