Based upon the circumstances at the time, were rockefeller's business practices justified? how did other captains of industry (carnegie, morgan, vanderbilt, etc.) conduct business in the late 19th century? what were the negative consequences of their actions? how did government and labor respond?

It was justified because he did what anyone else with the opportunity would do. His businesses practices were creating monopolies and trusts but what he was doing wasn't illegal up to a certain point in time when the courts decided to intervene. They all did it and they all became immeasurably wealthy. The government responded by introducing new laws to prevent such trusts and the labor was unsatisfied because they controlled everything.

  the domino theory states that  if one country in a region came under the influence of communism, then the surrounding countries would follow in a  domino  effect.