Answer:
The correct answer is the last option: Monopolistically competitive firms have market power and a downward sloping demand curve, so they set a price higher than marginal cost.
Explanation:
On the one hand, a perfect competitive market is characterized by the fact that it is a market where there are a lot of producers and they produce the same good so there is no differentiation and for that reason they can not charge what they want to the price but the market in its whole makes that decision and that is why at the long run the price equals the marginal cost establishing that there ir no interest for firms to enter or exit the industry.
On the other hand, a monopolistic competitive market is characterized by the fact that there are also a lot of producers that produce similar goods but they can charge a higer price to everyone of their products due to the fact that they are differentiated by the brands and their customer's loyalty and therefore that they have market power and at the long run when facing a downward sloping demand curve, they can set a price higher that marginal cost.