In the early 1990s, the state of Wisconsin pilot tested a variety of welfare reform programs such as Workfare and Learnfare. These programs helped the federal government reform its major welfare program in 1996. This is an example of

A. authority policy tools.
B. taxing and spending.
C. the politics of problem definition.
D. use of real-world situations to develop policies.

D. use of real-world situations to develop policies.