According to the court decision, what would be the result of state regulation of railroads?

Those laws were struck down in 1886, when the Supreme Court ruled in Wabash v. Illinois that the state of Illinois could not restrict the rates that the Wabash Railroad was charging because its freight traffic moved between the states, and only the federal government could regulate interstate commerce.

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b. the 200th birthday of the united states

i believe the answer is d.