Answer:
B) other firms can enter the market.
Step-by-step explanation:
In a monopolistically competitive market, there are lots of suppliers that offer differentiated products to lots of consumers, e.g. restaurants. In a monopolistic market, only one supplier exists.
In a monopolistically competitive market the barriers of entry are low, and other competitors can continually enter the market, while it is very difficult for other competitors to enter a monopolist's market.