D Question 11 3 pts Two drugs are tested to see which is a more effective sleep aid, Drug A or Drug B. Twenty patients were randomly assigned to Drug A and were given a gel bed topper, Another twenty patients were randomly assigned to Drug B and given a memory foam bed topper, At the end of the study, results were compared to see which drug was more effective in helping patients fall asleep. What is the biggest threat to the usefulness of this experiment? O lack of randomization problems with confounding O the placebo effect diagnostic bias O undercoverage 3 pts