How has hog raising changed in Oklahoma over the years? Fewer hog farms now exist.
More corporate focus has taken place.
It is limited to a few areas.
It has become the number one livestock commodity.

More corporate focus has taken place.

Explanation:

Oklahoma was a wheat growing nation but hog raising become the priority occupation for the nation. Greater increase in agricultural land, grain availability, and increase in export of hog to West coast contributed to the increase in the growth of profit obtained from the hog raring. Also increased access to water through aquifer contributed to the raring of hogs in the nation. All these facilities allowed the corporate to focus on the growth of hog industry.

your answer would be (a)

answer; (c) slaves brought to the americans from africa;