Economic Theory Suggests That the Optimal Level of Immigration in the United

Economic theory suggests that the optimal level of immigration in the United States

A) is zero.
B) occurs where the marginal benefit of the last immigrant equals or just exceeds the marginal cost of the last immigrant.
C) occurs where the marginal benefit of the last immigrant equals or just exceeds zero.
D) occurs at the level where the difference between the marginal benefit and marginal cost of the last immigrant is maximized.