We Assume That When a Firm Hires Additional Workers, the Marginal

We assume that when a firm hires additional workers, the marginal physical product of labor will

A) increase because more workers can always get more work done.
B) decrease because the new workers are likely to be less able than the previously hired ones.
C) decrease because each worker now has less capital and other resources to work with.
D) increase because large firms are more efficient.