Dr Fletcher Is Interested in Whether Joining a Fraternity/sorority Causes

Dr. Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance. He recruits a group of 55 freshmen (25 males, 30 females) who are planning to go through fraternity/sorority recruitment on his campus. After they join, he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale) .
In addition to measuring the Body Concern of the participants who joined a fraternity/sorority both immediately before and immediately after they join, Dr. Fletcher measures them for the 3 weeks before and the 3 weeks after. This type of design is known as a(n) :

A) nonequivalent control group design.
B) nonequivalent groups interrupted time-series design.
C) interrupted time-series design.
D) multiple-baseline design.