Answer» - The concept of selling cost is not seen in monopoly or perfect competition.
 - In monopolistic competitive market, the sellers try to attract the consumers by spending on advertisement, discounts, commission, attractive packaging, etc. All these form a part of selling expenses.
 - Selling cost creates product difference in the market which then gives a particular identity to a product. For example, companies manufacturing mobile phones, soaps, etc. try to create unique identity through selling costs.
 - Such a concept does not exist in perfect competition or monopoly. Hence, selling cost is a typical characteristic of monopolistic market.
  
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