The Mann-Elkins Act of 1910 extended the power of the Interstate Commerce Commission (ICC) over the railroad industry.
The Mann-Elkins Act was passed to strengthen the ICC's regulatory authority over the railroads by giving the commission the power to set rates and to regulate the practices of the railroads. The act also extended the ICC's jurisdiction to include telephone and telegraph companies, which were considered to be closely related to the railroads and were therefore subject to the same regulations.
The Mann-Elkins Act was an important step in the federal government's efforts to regulate the railroads and other industries in the early 20th century. It provided the ICC with greater authority to protect the public from discriminatory and monopolistic practices by the railroads, and it helped to ensure that the railroads would operate in the public interest.
So the correct answers are:
railroads
telephone
telegraph