Two Psychiatrists Conducted an Experiment to Test the Effectiveness of a New

Multiple Choice

Two psychiatrists conducted an experiment to test the effectiveness of a new drug expected to help people with obsessive-compulsive disorder (OCD) . The researchers tested 60 clients with OCD, randomly assigning 30 to a group that received the drug and 30 to a placebo control group that received a pill without the drug. The use of a placebo control group and random assignment are most closely related to which criterion for showing causation?

A) Eliminating plausible alternative explanations for why the drug might be effective
B) Covariation, or showing that the drug and OCD symptoms are associated
C) Time-order, or showing that the drug was administered before its effectiveness was tested
D) They are equally related to all three criteria for showing causation.