Help with History!!!

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.

If one thinks illegal immigrants should become american citizens, should they become american citizens automatically or should there be a waiting period? if there should be a waiting period, explain why.

Where were the trials to review evidence in cases against high-ranking nazi officials accused of war crimes held?