Students in a large statistics class were randomly divided into two groups. the first group took the midterm exam with soft music playing in the background, and the second group took the exam with no music playing. after the exam was completed, a researcher compared deidentified exam scores of the two groups. which of the following is the reason this experiment was not blind? a. the sample sizes in both groups was large. b. the students knew whether or not music was playing while they were taking the exam. c. students were randomized into the two groups. d. some of the students may not have studied for the exam. e. researchers looked at exam scores for the two groups.