Which of the following would be a valid conclusion to draw from the study?
(a) A teacher can improve his or her teaching evaluations by giving good grades.
(b) A good teacher, as measured by teaching evaluations, helps students learn better, resulting in higher grades.
(c) Teachers of courses in which the mean grade is above average apparently tend to have above-average teaching evaluations.
(d) Teaching evaluations should be conducted before grades are awarded.
(e) All of the above.