The correct answer is: A. Entry barriers
A perfect market is a theoretical market structure in which there are many buyers and sellers, there are no barriers to entry or exit, and goods are homogeneous. In a perfect market, firms are price-takers, meaning that they cannot influence the market price of their goods.
Entry barriers are factors that make it difficult or expensive for new firms to enter a market. These can include economies of scale, government regulation, and patents.
Interdependence is the state of being mutually dependent. In a market, interdependence occurs when firms are aware of each other’s actions and take them into account when making their own decisions.
Absence of selling costs means that firms do not incur any costs in marketing or selling their goods. This is because in a perfect market, there is no need for firms to differentiate their products or services, as all goods are homogeneous.
Non-price competition occurs when firms compete on factors other than price, such as product quality, customer service, or advertising. This is because in a perfect market, firms cannot influence the market price of their goods, so they must compete on other factors in order to attract customers.
In conclusion, the correct answer is A. Entry barriers.