For a large firm that produces and sellRefer to Table 14-2. At which number of workers does diminishing marginal product begin? a. 2 b. 4 c. 3 d. 1 s automobiles, which of the following costs would be a variable cost? a. The rent that the firm pays for office space in a suburb of St. Louis b. The cost of internet advertising incurred each year c. The cost of the steel that is used in producing automobiles d. The $20 million payment that the firm pays each year for accounting services