________ is an industry with a single firm in which the entry of new firms is blocked.

A) A monopoly
B) Monopolistic competition
C) An oligopoly
D) Perfect competition

Monopoly

A market structure characterized by a single seller that exercises exclusive control over a particular commodity or service, preventing competition.

Oligopoly

A market structure characterized by a small number of firms whose decisions about production and pricing significantly affect each other.

Perfect Competition

A market structure characterized by a large number of small firms, identical products, and no barriers to entry or exit, leading to price determination by market forces.