In the Long Run, Economic Profit Earned by a Monopolistically

In the long run, economic profit earned by a monopolistically competitive firm:​

A) is zero due to the lack of barriers to entry.
B) is zero due to the production of homogenous goods.
C) may be positive due to strong barriers to entry.
D) may be positive due to product differentiation.
E) may be positive due to advertising and product promotion.