Suppose an additional worker can handle an additional 10 orders per hour. That will cost $15 per hour. An additional telephone answering machine will handle an additional 20 calls per hour at a cost of $10 per hour. Which of the following is correct? A The firm should increase labor and decrease capital, because labor costs more per hour. B The firm should increase capital and decrease labor, because labor produces less per hour. C The firm should increase capital and decrease labor, because labor produces less per dollar spent. D The firm should increase labor and decrease capital, because labor produces less per dollar spent.