According to Research, When Do Students Become Engaged

According to research, when do students become engaged?

A) When they know they are getting a grade on the assignment.
B) When they know that they will have to skip recess if their work is not complete.
C) When they get to work in large groups.
D) When they are interested in a concept or activity.
E) When they receive a reward if they are able to do better than anyone elsE)