For his research methods class project, Hiro is studying the effect of pet ownership on stress levels. Although a lot of research has been done on dog and cat owners, not much is known about other pets so Hiro decides to study hamster owners. Which of the following would demonstrate a snowball sampling technique?
A) He is interested in hamster owners and not pet owners in general.
B) He recruits his hamster owners by e-mailing members of the National Hamster Owners Association and asking for participants.
C) His participants are all the people who have purchased hamsters at his local pet store in the past year.
D) He asks hamster owners to give him the names of other hamster owners.