Final answer:
From 1875-1920, the organization of industry in the United States involved vertical integration, horizontal integration, and trusts.
Step-by-step explanation:
From 1875-1920, the organization of industry in the United States underwent significant changes. During this time period, multiple methods of organization were utilized, including vertical integration, horizontal integration, and trusts. Vertical integration involved a company acquiring other companies that encompassed all aspects of a product's lifecycle.
Horizontal integration involved merging with or eliminating competition within a specific industry. Trusts were a legal arrangement where a group of trustees had ownership of and operated a business for the benefit of other investors. Therefore, the correct answer to the question is 4) All of the above.