...1a)	Perfect competition describes a market structure whose assumptions are extremely strong and highly unlikely to exist in most real-time and real-world markets. In perfect competition, there are a large number of firms in the industry. The firms in this industry are price takers as they sell at whatever price is set by demand and supply in the industry as a whole. All the firms produce homogeneous products which are exactly identical; it is impossible to distinguish between a good produced in one firm and a good produced in another firm. There are no barriers to entry or exit ; firms can enter or exit the market when they want to, however they don't have ability to stop new firms from entering and old firms from leaving the industry. Producers and consumers have perfect knowledge of the market i.e. the producers are fully aware of market prices, cost in the industry, and the workings of the market and the consumers are fully aware of prices in the market, the quality of the products, and the availability of the goods. Monopolistic competition is a market structure with many competed firms and each firm has a little bit of market power to set prices. The industry is made up of large number of firms and each firm is able to set prices and therefore it has a downward sloping demand curve. There is free entry and exit of firms in response to profits in the...