Respuesta :
it was : B-refining oil Back then, standard oil managed to gain monopoly within the oil industry by buying all of the existing rival refineries and united it under the standard oil brand. This allow them to dominate the whole oil product that distributed in united states
Answer: refining oil
Explanation:
Horizontal integration refers to a company that holds control over a specific part of the production process by managing most or even all of the resources required for that distinct step of production.
Furthermore, a company that gets to own every single part of the production process, is a horizontal monopoly. The idea of a horizontally integrated monopoly was made popular by John D. Rockefeller’s Standard Oil company.