DrFletcher Is Interested in Whether Joining a Fraternity/sorority Causes People

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