Answer:
barriers to entry; to a few oligopoly firms.
Step-by-step explanation:
Occasionally, barriers to entry may lead to pure monopoly; in other market conditions, they may limit competition to a few oligopoly firms.
Monopoly can be defined as a type of market in which there is a single seller of a unique product. This sellers typically do not face any competition from others.
This ultimately implies that, when there are barriers to entry it may result in monopolistic competition among the sellers of goods having no close substitutes. These barriers consist of economies of scale, network externalities, copyright law, trademark, patent, governmental policies etc.