The correct answer is A) immigration provided a large number of low-cost workers for U.S. businesses.
Immigration contributed to economic growth after the civil war in that immigration provided a large number of low-cost workers for U.S. businesses.
After the civil war, many cities in the Northern states benefited from new fabrics, manufacturing jobs, and railroad. Immigrants that entered the United the States after the Civil War could get low paid Jobs in those industries. Indeed, they contributed to economic growth after the civil war in that immigration provided a large number of low-cost workers for U.S. businesses. Even black people from the Southern states emigrated to the North in order to look for better living conditions and better Jobs tan farming.