At the beginning of a call to the cable company, a message tells customers, “after you finish talking to our customer service representative, you will be asked to take a five-question survey about the level of service you received. it would be appreciated if you could stay on the line to answer the survey questions.” what type of sampling is the cable company using?

Which of the following statements is (are) true? i. free entry to a perfectly competitive industry results in the industry's firms earning zero economic profit in the long run, except for the most efficient producers, who may earn economic rent. ii. in a perfectly competitive market, long-run equilibrium is characterized by lmc < p < latc. iii. if a competitive industry is in long-run equilibrium, a decrease in demand causes firms to earn negative profit because the market price will fall below average total cost.