As a result of World War I, what happened to the federal government in the United States?

The scope of its power increased.

The scope of its power decreased.

It grew increasingly more isolationist.

The people lost trust in its ability to keep America out of war. - wrong

The best option would be that as a result of World War I, generally speaking " It grew increasingly more isolationist," since Americans felt as though thousands of American lives had been "wasted" in the war. Although American international power did indeed increase.