Which of these would be considered an example of vertical

Last updated: 7/29/2022

Which of these would be considered an example of vertical integration? Standard Oil controlling 90% of the oil industry The Industrial Workers of the World (IWW) being a union that was open to all workers, even unskilled immigrants Political machines providing immigrants with jobs in exchange for votes Carnegie Steel owning the mines that produced the iron it would make into steel, as well as owning the boats that brought the iron to the steel mills