How did Rockefeller use horizontal integration? A.
by controlling all aspects of the production process
B.
by using huge profits to eliminate his competitors
C.
by getting an exclusive government contract
D.
by buying out all the competing oil companies

I think its D but im not all the way sure

Explanation:

Rockefeller used horizontal integration to build the Standard Oil empire by making agreements with railroads. Rockefeller's business was big enough that he could negotiate favorable rates for transporting oil because he was transporting a lot of oil and the railroads wanted his business

the right choice would be a. culture within the city-state. c. loyalty to the police. d separation by land and sea.

the difference is that white collar worker performs skills like worker as a scientist or well blue collars do physical work and they do services like being a cook.