Labor unions create barriers to entry in certain work settings

To a firm facing constant input prices, increasing marginal returns

a. means that each additional unit of output costs more to produce than the previous unit b. means that the marginal product of the variable input decreases as more of the input is used c. can occur due to specialization and division of labor d. usually occur at very high rates of output e. can never occur

At a firm's profit-maximizing level of output, its price is $200 and its short-run average total cost is $225 . The firm

a. has a profit of $25 per unit of output. b. should shut down if its short-run average fixed cost is less than $25. c. has a loss of $100 per unit of output. d. should shut down if its short-run average variable cost exceeds $25.