If firms in a monopolistically competitive industry are earning economic profits, then in the long run:

a. these firms can continue earning economic profits because entry into the industry is blocked.
b. new firms producing close substitutes will continue to enter the market until economic profit is zero.
c. new firms producing the exact same product will enter the industry and this entry will continue until economic profit is zero.
d. the government will most likely regulate firms in this industry to reduce the economic profits.

"jake’s roof repair has provided the following data concerning its costs: fixed cost per month cost per repair-hour wages and salaries $ 20,900 $ 15.00 parts and supplies $ 7.70 equipment depreciation $ 2,800 $ 0.35 truck operating expenses $ 5,720 $ 1.60 rent $ 4,690 administrative expenses $ 3,850 $ 0.50 for example, wages and salaries should be $20,900 plus $15.00 per repair-hour. the company expected to work 2,600 repair-hours in may, but actually worked 2,500 repair-hours. the company expects its sales to be $47.00 per repair-hour. required: compute the company’s activity variances for may."