A psychologist designs a study to investigate the effect of diaphragmatic breathing on test anxiety. After recruiting test-anxious subjects, the researcher splits the group so that two equivalent groups are created. One group is taught this method of breathing and asked to use it before taking a verbal memory test, while the other group is not taught the technique. After scoring the tests and conducting a statistical test, the researcher finds that the group that received the training significantly outperformed the other group. In this design, the test scores for each group would be .

a. an example of a correlational outcome
b. the independent variable
c. the dependent variable
d. considered random