Final answer:
The methods used by industrialists in big business to achieve success were horizontal and vertical consolidation. Horizontal consolidation involves taking over competitors in the same industry, while vertical consolidation controls the entire supply chain.
Step-by-step explanation:
Methods used by industrialists in big business to be successful included both horizontal consolidation and vertical consolidation. Horizontal consolidation refers to the process of a company increasing its size by taking over its competitors in the same industry, often leading to monopolies.
An example of this would be John D. Rockefeller's Standard Oil Company, which took control of other oil companies to dominate the oil industry.
On the other hand, vertical consolidation involves taking over all the different businesses on which a company relied for its primary function, thus controlling the entire supply chain from raw materials to final product delivery, as demonstrated by Andrew Carnegie's Carnegie Steel Company.
In contrast, Natural selection is a concept from biology, referring to the process by which organisms better adapted to their environment tend to survive and produce more offspring. This principle of biology was inappropriately co-opted by some industrialists to justify their business practices under the guise of social Darwinism, which advocated a minimal regulatory approach to economy and society, allowing for the 'fittest' businesses to survive ostensibly without external aid or intervention.