In differential research, assignment of participants is

Celebration, Florida, is notable for

a. its city plan, which calls for homes to re-create the atmosphere of the pre-World War II small town. b. a mixture of both expensive and low-cost housing. c. a model school given a financial boost from the Walt Disney Company. d. All of the above

Congress taking over the regulation of warnings on cigarette packages from individual states is an example of

A) ?preemption. B) ?nullification. C) ?direct democracy. D) ?implied powers. E) ?licensing.