How are courts of appeals different from district courts?

An education expert is researching teaching methods and wishes to interview teachers from a particular school district. she randomly selects ten schools from the district and interviews all of the teachers at the selected schools. which type of sample did she use in this study? a)systematic sample b)probability sample c)stratified sample d)cluster sample

Which of the following starements is true based on the above information?

Why did the athenians choose officials by lottery? would there be drawbacks to this method? explain.