A profit-maximizing firm will use less of a factor of production when:
A. The extra cost of using an additional factor unit is greater than the marginal physical product (MPP) of the additional factor unit.
B. The marginal physical product of the additional factor unit is greater than the marginal revenue product (MRP) of the additional factor unit.
C. The extra cost of using an additional factor unit is greater than the marginal revenue product of the additional factor unit.
D. The marginal physical product of the additional factor unit is less than the marginal revenue product of the additional factor unit.