what made standard oil a horizontal integration monopoly? it owned ninety percent of us oil refineries. it…

what made standard oil a horizontal integration monopoly? it owned ninety percent of us oil refineries. it controlled all aspects of oil production. it operated all across the united states. it formed a trust.
Answer
Brief Explanations:
Horizontal integration is combining many firms in the same business. Owning 90% of US oil refineries means Standard Oil had combined a large portion of firms in the oil - refining business, creating a monopoly. Controlling all aspects of oil production is vertical integration. Operating across the US doesn't define horizontal integration. Forming a trust is a method but not the defining characteristic of horizontal integration here.
Answer:
It owned ninety percent of US oil refineries.