Answer:
The correct answer is option a.
Explanation:
An oligopoly market is a market structure where there are a few firms in the market. Because of a few firms, there is a high degree of interdependence and competition in the market.
As the number of firm increases in such a market, the market approaches the perfectly competitive outcome where the output and price are socially optimal.
In a perfectly competitive firm, there is a large number of firms. As the number of firms increases, the output will move towards a competitive level.