Aschool has 5000 students. there are 1500 freshman, 1500 sophomores, 1000 juniors, and 1000 seniors. at 8: 00 am, all students are in class; there are 200 classes that each have 25 students. the administration wants to give a survey asking the students about their favorite classes. they wish to poll 100 students. the entire student body is assigned a number, and then a random number generator is used to select 100 of those numbers at random. the students matching those numbers are given the survey. what sampling method was used?