What was the primary purpose of the Interstate Commerce Commission after its establishment?

The primary purpose of the Interstate Commerce Commission (ICC) after its establishment in 1887 was to monitor business operations of transportation carriers, particularly railroads. The ICC was created in response to growing concerns about the monopolistic practices of railroad companies and the unfair rates charged to farmers and small businesses.

By overseeing the practices of railroads and later extending its jurisdiction to other forms of transportation, the ICC aimed to ensure fair rates and eliminate discriminatory practices. This regulatory role was central to its mission, as it sought to protect the interests of consumers and maintain a level playing field in interstate commerce. The commission was empowered to investigate complaints and enforce regulations, making it a crucial body in shaping economic policies related to transportation in the United States.

The other options do not accurately reflect the ICC's goals. The ICC was focused on regulation, not deregulation; it did not promote railways exclusively but instead aimed to regulate their practices; and it was not involved in managing agricultural output directly. These points highlight why monitoring business operations was the commission's correct focus.