Why Was It Necessary for Railroads and Land Speculators to Promote

Why was it necessary for railroads and land speculators to promote settlement of the Great Plains in the late nineteenth century?

A) The U.S.government had not publicized the Homestead Act.
B) Americans thought of the area as the Great American Desert.
C) Without economic incentives,few people could afford homesteads.
D) The region was heavily forested and hard to cultivate.