Suppose That a Perfectly Competitive Industry Is in Long-Run Equilibrium

Multiple Choice

Suppose that a perfectly competitive industry is in long-run equilibrium. Then the price of a complement good decreases. What will happen?

A) Next period a typical firm will increase output.
B) Next period a typical firm will earn positive economic profit.
C) Eventually firms will exit the industry.
D) both a and b
E) all of the above will happen