Question

Samuel is researching the extracurricular activities that all of the teachers at his school participated in when they were in school. He interviewed a number of teachers for each subject in the school that was proportional to the total number of teachers in the school for that subject. Which of the following is not true?

A] The teachers in his grade are the sample.

B] The population is all teachers in his school.

C] He used stratified sampling.

D] Each teacher that he interviewed is a unit in the study.