Which enable an oligopoly to form within a market?

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The correct answer is the costs of starting a competing business are too high.

What helps enabling an oligopoly to form within a market is the costs of starting a competing business are too high.

There are three basic conditions that are present when forming an oligopoly. The first one is that an oligopoly has few large Corporations. Secondly, in a monopoly, there is only one corporation. In an oligopoly market, there are high barriers to entry. The costs of starting a competing business are too high. And finally, the products oligopolistic corporations produce are differentiated of homogenous.  

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