Monopolies Can Earn Positive Economic Profits in the Long Run

Monopolies can earn positive economic profits in the long run while monopolistically competitive firms cannot due to

A) economies of scale in monopolies but not in monopolistic competition.
B) barriers to entry in monopoly but not in monopolistic competition.
C) market power of monopolies while monopolistically competitive firms have no market power.
D) the less elastic demand faced by monopolies as compared to monopolistically competitive firms.