When Firms in Monopolistic Competition Make an Economic Profit

When firms in monopolistic competition make an economic profit,

A) firms enter the industry,which increases demand for the product of the firms originally in the market.
B) firms exit the industry,and demand increases for the products of the firms that remain.
C) firms exit the industry,and demand decreases for the firms that remain in the industry.
D) firms enter the industry,and demand decreases for the firms that were originally in the industry.
E) eventually the market will become a monopoly.