Students in a large statistics class were randomly divided into two groups. the first group took the midterm exam in a room painted in pale green while the second group took the exam in a room painted bright yellow. the exam scores of the two groups were then compared. this experiment was not blind because: (a) the students knew which color the room in which they took the exam was painted.(b) students were randomized into the two groups.(c) the exam was too long.(d) some of the students did not study for the exam.(e) students were allowed to keep their eyes open while taking the exam.