A Human Service Professional Is Interested in Studying Whether EMDR

A human service professional is interested in studying whether EMDR (Eye Movement Desensitization and Reprocessing Therapy) is effective in reducing trauma-related symptoms among returning veterans from active combat duty in Afghanistan. Reduction in the scores on the PTSD scale would indicate the therapeutic modality's effectiveness in reducing trauma related symptoms. Therefore, in this study, the professional would:

A) examine the data to see whether there is a correlation between the pretest and the posttest scores on the PTSD scale
B) examine the data to see if there is statistical significance
C) examine the data to see whether there is statistical significance of the mean difference and whether the posttest scores is higher than the mean of the pretest
D) examine the data to compute the average of the posttest score only