Ms Johnson's Sixth Graders Complained About Diagramming Sentences, and They

Ms. Johnson's sixth graders complained about diagramming sentences, and they were able convince her to show a movie first. Ms. Johnson made the common error of

A) bribing the students in order to gain their cooperation.
B) promising a reward for an unflavoured activity.
C) providing an incompatible alternative to the lesson.
D) using a reinforcer before a low-frequency behaviour.