During world war i, federal agencies expanded the national government's role by

The correct answer is that they established the eight-hour workday for the workers and gave them really generous overpay.

This means that the government did intervene in the business which was something not really common in the United States of that period since the concept of the free market was really strong at the time and people resisted any interference by the government. Government took more active role in the market after the Great Depression.