A Perfectly Competitive Firm Can Continue to Earn Above-Normal Profit

A perfectly competitive firm can continue to earn above-normal profit in the long run

A) if it has a continued technical advantage over other firms in the market and it is able to keep that advantage a secret
B) if it has employees that are substantially more efficient than other firms' workers
C) if its centralized location reduces its transportation costs below those of other firms
D) if it has easier access to necessary raw materials
E) under no circumstances