高階ECON-MSTR-020
A high barrier to entry is most important for explaining why:
A. A perfectly competitive firm faces a horizontal demand curve.
B. Marginal cost slopes upward.
C. A monopoly can keep earning economic profit in the long run.✓ 答案
D. Consumers prefer lower prices.
解說
Without a barrier, profit attracts entry and the demand facing the incumbent shrinks. A barrier stops that entry, so long-run economic profit can remain. The competitive firm’s horizontal demand comes from being a price taker, not from a barrier.