Suppose That a Long-Run Adjustment in a Perfectly Competitive Industry

Multiple Choice

Suppose that a long-run adjustment in a perfectly competitive industry results in decreased industry output but leaves price unchanged.Which of the following must be true?

A) The market demand curve did not shift
B) The market demand curve shifted left; the market supply curve shifted right
C) The market supply curve shifted left; the market demand curve shifted right
D) Both market supply and demand increased, but supply increased more than demand
E) The industry is a constant-cost industry