contestada

"What was the primary cause of the trends shown on the graph?
(1)closing of the western frontier
(2)industrialization in the North and the Midwest
(3)passage of the Homestead Act
(4)completion of the transcontinental railroad"

What was the primary cause of the trends shown on the graph 1closing of the western frontier 2industrialization in the North and the Midwest 3passage of the Hom class=