Refer to the Following Paragraph to Answer the Questions Below

Refer to the following paragraph to answer the questions below.
Professor Alco Drunkman studied class level and drinking behavior at Wild State University in Boozville, Texas. Every student is required to live in one of six twenty-story-tall dormitories, and has a single room. All dormitory room phone numbers began with the prefix 747 or 757 (e.g., phone numbers are 747-0001 to 757-9999) . He used the student telephone directory, and after a random start selected every 15th student. He then mailed a questionnaire to the 1,000 students selected and had two follow-up postcard reminders. A total of 900 students returned questionnaires. Later, he asked the university registrar whether any students were omitted from the directory.
-Drunkman wants to mail out questionnaires, but he wants to be certain that the sample contains an equal number of freshman, sophomore, junior, and senior students. He asks you to draw a stratified sample. What is the best way to draw the sample?

A) Choose every 10th, instead of 15^th, name when selecting students.
B) Use the registrar's list of students instead of the telephone directory, and select every 15th student name.
C) Get a list of each class (e.g., freshman, sophomore) from the registrar and use a random number table or program to select 500 names from each class.
D) Open up the phone book to a random page and begin calling up students listed. Ask them what class they are in, then send questionnaires to the first 500 who say "freshman," the first 500 saying "sophomore," etc.
E) First randomly select 10 dormitories, then randomly select every other floor of the 10 selected dormitories, then mail questionnaires to students on the students living in rooms on the selected floors.