HELP DOWN BELOW

Also don't mind the answer I chose, it was on accident.

How was rockefeller able to build his monopoly across the oil industry? he found newer and cheaper ways to refine oil, increasing his profits. he confined his business to ohio so he could buy all the refineries there. he bought up oil refineries, cut costs, and reinvested his profits in other refineries. he began to sell kerosene as well as oil, expanding his market.

30 in 1566 the i belonged to spain. ii rebelled against spanish rule. iii was in independent country. iv was made up of both catholic and protestant provinces.

How does the power of the supreme court act as a check on the other branches of government