The term oligopoly indicates an industry whose four-firm concentration ratio is low. many producers of a differentiated product. a one-firm industry. a few firms producing either a differentiated or a homogeneous product.

A few firms producing either a differentiated or a homogeneous product.

Explanation:

Oligopoly is a type of market economy which is shared by few suppliers. There are two types of oligopoly markets, homogeneous and differentiated. This type of market is considered as highly concentrated. The three important characteristics of oligopoly market are; small number of firms, barriers to entry and identical and differentiated both goods are sold in this market.

the answer would be voluntary exchange -

"the act of buyers and sellers freely and willingly engaging in market transactions. moreover, transactions are made in such a way that both the buyer and the seller are better off after the exchange than before it occurred."

hope this : )

-shy