One Professor Assigned Three Papers in His Class

One professor assigned three papers in his class. Then, she let students decide between firm deadlines spread out or having the flexibility to turn in the papers at any time during the semester. What were the results, on the average?

A) The quality of the papers was about equal, regardless of the deadlines.
B) Those who set rigid, spread-out deadlines for themselves did better.
C) Those who allowed themselves more flexibility did better.
D) Average students did better with firm deadlines, but the top students did better with flexibility.