If companies earn economic profits in a perfectly competitive market,over the long run the supply curve will most likely:
A. shift to the left.
B. shift to the right.
C. remainunchanged.
我的理解是有超额收益，新的竞争者进入会分走一部分需求，则现存公司供应减少

从长期来看，完全竞争会走向垄断竞争吧，那如果公司一直都能有profits存在，那它的supply应该是增加的吧。

应该选c吧

B