The correct answer is: "a school board that oversees public education for several communities".
A special-purpouse district, within the US administration, is a goverment unit created to serve a specific objective and separated from local goverments, such as those which govern a town, city, county, etc, hence enjoying administrative and fiscal independence. For instance, school boards are one example as they are fully dedicated to the educative function and other aspects related to it.
