Aschool psychologist wants to test the effectiveness of a new method of teaching art. she recruits 600 second-grade students and randomly divides them into two groups. group 1 is taught by means of the new method, while group 2 is taught via traditional methods. the same teacher is assigned to teach both groups. at the end of the year, an achievement test is administered and the results of the two groups compared. what is the response variable in this experiment?
a. the students’ ability in art
b. the score of group 1 on the achievement test
c. the score on the achievement test.
d. the score of group 2 on the achievement test