the answer is: C. perfect competition
In a prefect competition, all competitors in a certain market operates without having any competitive advantage over one another beside their selling techniques.
One advantage of this type of market is that it's convenient for the costumers, since they do not have to conduct in prolonged bargaining fearing that the sellers would give them an overpriced product.
One disadvantage of this type of market is that it provide the customers with very little options due to the similarity of price and type of products sold in the market.