"boom" times for the mining, cattle, and agricultural industries (or "frontiers") in the american west followed what common pattern?
a. at first, individuals sought quick profits; eventually, large-scale corporate enterprise took over with hired labor.
b. at first, white settlers exploited natural resources; eventually, later arrivals lived in harmony with the environment.
c. at first, great wealth was controlled by only a few ranchers and mining barons; eventually, most homesteaders got rich.
d. at first, towns sprang up; eventually, railroads were constructed to connect them.