38. A perfectly competitive producer of steel rods and steel beams employs 100 workers with identical sldlls. If steel rods and steel beams sell for the same price, which of the following rules should the producer always follow to use the 100 workers eiciently? I. Allocate workers so that the average cost of producing beams equals the average cost of producing rods. II. Allocate workers so that the marginal product of labour is the same in both rod production and beam production. III. Allocate half the workers to rod production and half the workers to beam production. A. I only B. II only C. III only D. II and III only E. I, H, and