This account shows the importance of what economic factor in the development of industrialization in the United States?

Quick using the information in the graph, one might speculate that a) w. w.i created increased job opportunities in the u. s. b) the election of president hoover in 1936 caused unemployment to decline. c) the return of soldiers following w. w.ii caused unemployment to increase in the u. s. d) the new deal programs of president roosevelt created employment opportunities in the u. s.