In Order to Encourage Students Who Are Concerned About Their

In order to encourage students who are concerned about their GPAs to take harder classes, professors of these classes should:

A) grade on a curve because it increases students' incentive to study even when the material may be hard.
B) grade on a curve because it increases students' incentive to study even when some students in the class may be smarter than others.
C) not grade on a curve because grading on a curve will only serve to reduce students' incentive to study, particularly if the material is hard.
D) not grade on a curve because grading on a curve will only serve to attract lower-level students who are less likely to study.