Parts of the retail industry in which a small number of businesses control a large portion of the market represent

direct competition

oligopolies

price competition

monopolies

The answer to your question is "Oligopolies."

An oligopoly is a market form where a market is controlled by a few large sellers or businesses.  The type of market is going to effect the price in one of two ways.  The first possibility is that the few businesses will work together, or collude, in order to establish higher than normal prices.  The second possibility is that there will be fierce competition between the few sellers, which will result in a high level of competition and lower prices.

answer; ///i believe that the correct answer is (a) it is the means by which a person earns money;