A Professor Constructs a Questionnaire to Determine How Students at the University

A professor constructs a questionnaire to determine how students at the university feel about nuclear disarmament. Which of the following techniques should be used in order to survey a random sample of the student body?

A) Every student should be sent the questionnaire.
B) Only students majoring in psychology should be asked to complete the questionnaire.
C) Only students living on campus should be asked to complete the questionnaire.
D) From an alphabetical listing of all students,every tenth (or fifteenth,e.g.) student should be asked to complete the questionnaire.