B: The act gave the government the power to set and limit shipping costs.
Before the Hepburn Act was enacted in 1906, the Supreme Court was the responsible one in controlling the prices railroads could charge and have the final say in the matter, even though it existed a regulatory agency (The Interstate Commerce Commission) to do that.
The new Act strengthened federal regulation of railroads and gave the Interstate Commerce Commission (ICC), a regulatory agency, more power to regulate railroads by setting maximum prices rates and other practices.