B) Eureka High School has 400 freshman, 300 sophomores, 300 juniors, and 200 seniors. The student newspaper conducts a poll asking if the football coach should be
fired. The newspaper randomly selects 20 freshman, 15 sophomores, 15 juniors, and 10
seniors for the poll. what type of sampling is being used?

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.