Explanation : Even though there are only four firms in the industry, the barriers to
entry are low. This implies that other firms are voluntarily not entering
the industry, making this most likely a perfectly competitive
environment.
Explanation : There are many competitors in the market, but there is evidence of
branding and product differentiation. These are characteristics of
monopolistic competition.
Explanation : Oligopoly markets are characterized by a small number of firms that
dominate the market. There are so few firms in the relevant market that
their pricing decisions are interdependent.