A Market Researcher Showed a New Brand of Designer Jeans

A market researcher showed a new brand of designer jeans to several groups of college students and asked the students to rate their quality.Two weeks later,the researcher showed the same college students a television advertisement featuring movie star Scarlett Johansson wearing the new brand and asked the students again to rate the quality of the jeans.The marketer predicted that after viewing the advertisement,the students' ratings of the new jeans would be more positive than their original ratings.In this experiment,students' ratings of the new blue jeans served as the

A) dependent variable.
B) independent variable.
C) social environmental force.
D) secondary data.
E) constraint.