This Figure Shows the Payoffs Involved When Sarah and Joe

Multiple Choice

This figure shows the payoffs involved when Sarah and Joe work on a school project together for a single grade.They both will enjoy a higher grade when more effort is put into the project,but they also get pleasure from goofing off and not working on the project.The payoffs can be thought of as the utility each would get from the effort they individually put forth and the grade they jointly receive.
Assume that Joe and Sarah,from the figure shown,are also dating,in addition to working together on the joint school project.Further assume that Joe is madly in love with Sarah,who is an excellent student.Sarah tells Joe that she will break up with him if he does not put forth high effort on this project.This future punishment by Sarah is an example of:

A) a commitment strategy.
B) an effort optimization strategy.
C) an ultimatum.
D) a bargaining strategy.