The Faculty of Business Studies of Dhaka University claims that the Faculty could save thousands of taka each year by turning services like garbage collection over to private companies. Which of following would provide the strongest ground for the Faculty's argument?

A    Statistics showing how much the Faculty spends each year on these services

B    Statistics showing how much comparable Faculties have saved by turning over these services to private companies

C    Statistics demonstrating how much more  the average student would have to pay more for privatization of these services

D    A direct comparison of how much the Faculty spends per year on this services  and how much the Faculty would save by turning over the services out to private companies