Consider the following studies being run by three different AP Statistics instructors.
I.One rewards students every day with lollipops for relaxation, encouragement, and motivation to learn the material.
II.One promises that all students will receive A's as long as they give their best efforts to learn the material.
III.One is available every day after school and on weekends so that students with questions can come in and learn the material.
A. None of these studies use randomization.
B. None of these studies use control groups.
C. None of these studies use blinding.
D. Important information can be found from all these studies, but none can establish causal relationships.
E. All of the above.