Answer:
The answer is D. occur when the buyer or seller has an influence on the price.
Step-by-step explanation:
Examples of imperfect market are monopoly and oligopoly.
In monopoly,there are many buyers and only one seller. This one seller has a controlling influence over the price of his goods and services. He has influence over the price.
In oligopoly, there are few firms or sellers and many buyers. They collude to set price. They influence the market price. Example of oligopoly is OPEC.
In imperfect market, barrier to entry is high and exit costs are usually high too