Why is the demand for a good under monopoly is inelastic than under monopolistic competition?

Under monopoly, the products produced by the seller has no substitute. This suggests that even with a rise or fall in the price, the demand of the product does not change much. This implies that the demand curve faced by the seller is inelastic. As against this, under a monopolistic competition, the products of different firms are close substitutes of each other. The products are very much similar to each other and perform the same basic function. This suggests that with a slight increase (or, decrease) in the price of the product, demand of the product would decrease (or, increase) by a large extent. It is due to this fact that the demand curve faced by a seller under monopolistic competition is elastic. 
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