Which of the following events will induce firms to enter an industry? Which will induce firms to exit? When will entry or exit cease? Explain your answer.

a. A technological advance lowers the fixed cost of production of every firm in the industry.

b. The wages paid to workers in the industry go up for an extended period of time.

c. A permanent change in consumer tastes increases demand for the good.

d. The price of a key input rises due to a long-term shortage of that input.