How would you classify the office superstore industry? Who are the competitors? What are the characteristics of this industry that lead to this conclusion?

Perfectly competitive is the most competitive market structure, and it is rare to observe in the world. It requires that the market's products be homogeneous, meaning there is not any brand differentiation - you cannot tell one firm's product from another in a perfectly competitive market. This is not true of the office superstore industry.

A monopoly, in which only one firm exists, is the least competitive industry. In the office superstore industry we have two main competitors (Staples and Office Max/Office Depot), so it cannot be a monopoly.

Monopolistically competitive is a fairly competitive market structure, characterized by product differentiation and competition in the industry among many firms. You would not see two firms dominating the market, so that rules out the monopolistically competitive industry in this scenario.

Finally we have a market structure that has become increasingly common to observe in the recent decades of merger mania: oligopoly. The office superstore industry is an oligopoly because it is dominated by a few small firms (Staples and Office Max/Office Depot) and is able to keep other firms out through barriers to entry. Specifically, economies of scale create a strong barrier to entry, since these two large firms have been able to get their cost per unit so low due to their high volume that new startups would not be able to compete on price. Sure, you can buy a limited selection of office products at Walmart or from Amazon, but for a true superstore experience in most areas you have two choices. Thus, the office superstore industry is an oligopoly.