A counselor wishes to examine the benefits of a parenting class on parenting skills. He decided to administer a questionnaire to the 10 parents who have attended the most recent class. How could this study be improved? Select all that apply. A. Increase the sample size B. Administer a questionnaire to parents who have not attended the class C. Give some sample responses, prior to administering the questionnaire. D. Uses a random sample of all patients, who have attended the class.