What was the core business that made standard oil a horizontally integrated monopoly?

He bought another businesses and products in order to increase or expand his business further. Refining oil was the business that made the standard oil a horizontal monopoly.

The government was though against the illegal monopoly. He bought other businesses which decreased the cost of production. This helped him increase his profits and business to such an extent that there was no other competitor in the market.

It owned 90% of the oil refineries in United States. Hence explaining the monopoly.

answer: born in saint-dié, in the vosges department, france, he studied law, and was called to the bar at paris in 1854,[2] but soon went into politics, contributing to various newspapers, particularly to le temps. he attacked the second french empire with great violence, directing his opposition especially against baron haussmann, prefect of the seine department. a series of his articles in le temps was later republished as the fantastic tales of haussmannlaxupa (1868).[2]

explanation:

the correct answer is a: slaves from other colonies ran away to georgia.