Western Booms Followed What Typical Pattern

Western booms followed what typical pattern?

A) Initially, settlers showed respect for the environment; later immigrants practiced ruthless exploitation.
B) Initially, there was accommodation with the Indians; ultimately, a war of extermination was pursued.
C) Initially, homesteaders sought new farmlands; eventually, the cattle barons displaced the farmers.
D) Initially, individuals rushed in for quick profits; then, corporations moved in with hired labor.