The state of Michigan promulgated a statute - the Solid Waste Management Act - which contained certain waste import restrictions. Specifically, the Act provided that solid waste generated in another country, state, or county could not be accepted for disposal unless explicitly authorized by the receiving county in the state. One county in Michigan thereby denied an application from a landfill company to have its out-of-state waste disposed of in the county's landfill. The landfill company contended that the Act was unconstitutional. What is the best statement regarding this dispute.

A. The state law was unconstitutional because it violated the commerce clause due to the discrimination against out-of-state waste, which is a form of interstate commerce.

B. The law was valid under the traditional "police powers" of the state.

C. The law was an unconstitutional infringement of the freedom of expression of the landfill company.

D. The law was valid since wanted to protect the health and safety of its residents.