For a study analyzing the difference between test scores before and after a treatment was applied, which statistic would be most appropriate for this study?

A) z-test for one mean
B) t-test for one mean
C) t-test for independent means
D) t-test for dependent means

A t-test for dependent means, also known as a paired-sample t-test, is appropriate for analyzing the difference between test scores before and after a treatment because it specifically compares the means of two related samples (in this case, the same individuals' scores before and after the treatment). Other options, such as a z-test for one mean or a t-test for independent means, are not appropriate as they do not take the relationship between the two sets of scores into account.