Can someone help me with this? THanks.

Monopoly is a market structure with two or more sellers of one product. * Perfectly competitive and monopolistically competitive markets have relatively no or slight barriers to entry. * A duopoly is a variation of monopoly. * Firms in oligopolies are generally larger than those in perfectly competitive markets. * Perfectly competitive and monopolistically competitive markets are different in terms of differentiation of products they sell. * Manufacturing converts inputs to outputs. * Merchandising involves buying goods and selling these for generally higher prices. * Two businesses may sell the same product but may have different business models. ' Facebook is an example of a business earning from using the advertising business model. *