In 1887, congress passed which of the following pieces of legislation to regulate railroads?

You did not add following but it was  the  interstate commerce act of 1887, the outcome was creation of tnterstate commerce commision  which original purpose was to regulate the railways, and later trailer transport, to ensure fair prices, eliminate price discrimination and regulate other aspects of transport, including public transport by bus between states and telecom companies. authority was dissolved on 1 january 1996 and its remaining functions were transferred to the surface transportation board.

Ithink the answer is a.