When marginal cost equals price in a perfectly competitive product market at long run equilibrium, which of the following is NOT correct?
(A)There is a socially optimal or efficient output and price. (B)Other product markets are inefficient by contrast. (C)It is a sign of high concentration among sellers. (D)The value placed on the product by the buyer is equal to the cost of production of the seller at the margin of an additional sale.
C