In the Long Run,a Firm in a Perfectly Competitive Market

In the long run,a firm in a perfectly competitive market operates

A) at its efficient scale,and a monopolistically competitive firm operates at efficient scale.
B) at its efficient scale,and a monopolistically competitive firm operates with excess capacity.
C) with excess capacity,and a monopolistically competitive firm operates with excess capacity.
D) with excess capacity,and a monopolistically competitive firm operates at its efficient scale.