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

Multiple Choice

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 group of participants who joined a fraternity/sorority, Dr. Fletcher decides to give the same measure to another group of 55 participants who decided to not join a fraternity/sorority. Doing this would help Dr. Fletcher address all of the following threats to internal validity EXCEPT:

A) Experimenter bias
B) Maturation
C) Selection
D) History