Dr. Xi conducted an experiment on the effectiveness of an antidepressant medication. Given her research design, if she finds that the drug is effective, which of the following will she be able to conclude? Antidepressants are related to reduced depression, because she found a negative correlation between depression levels and the administration of antidepressant medication. A Placebos are just as effective as antidepressants in treating depression, because she found that both placebos and antidepressants decreased depression by the same amount. B Antianxiety medication is related to reduced depression, because she found a negative correlation between depression levels and the administration of antianxiety medication. C Antidepressants decrease the severity of depression, and the experiment demonstrates cause-and-effect because she used random assignment. D Antidepressants decrease the severity of anxiety, and the experiment demonstrates cause-and-effect because she used random assignment.