Khalad Is Conducting a Study to Determine If Motivational Posters

Khalad is conducting a study to determine if motivational posters inspire middle school students to be more pro-social and to complete more homework. He goes to a large school district to conduct his study. In one of the district's middle schools he puts the posters up and in the second school he does not. After the posters are up for two months he compares the GPA and number of disciplinary referrals between the two schools.
-Which of the following represents the dependent measure in Khalad's study?

A) Pro-social behavior
B) Homework completion
C) Disciplinary referral
D) Motivational poster